Proposal summaries

These are research proposals that have been approved by the ALSPAC exec. The titles include a B number which identifies the proposal and the date on which the proposals received ALSPAC exec approval.

Click here to export results in Word format.

B674 - Biobank methods proposal - 30/06/2008

B number: 
B674
Principal applicant name: 
Dr Susan Ring (University of Bristol, UK)
Co-applicants: 
M Yuille (Not used 0, Not used 0), B Oliver (Not used 0, Not used 0)
Title of project: 
Biobank methods proposal
Proposal summary: 

No outline received

Date proposal received: 
Monday, 30 June, 2008
Date proposal approved: 
Monday, 30 June, 2008
Keywords: 
Genetics
Primary keyword: 

B673 - Provision of demographic variables from ALSPAC cohort to link with CDR gathered variables during TF2 - 27/06/2008

B number: 
B673
Principal applicant name: 
Mr Brian Saxby (Not used 0, Not used 0)
Co-applicants: 
Title of project: 
Provision of demographic variables from ALSPAC cohort to link with CDR gathered variables during TF2.
Proposal summary: 

The collaboration between Cognitive Drug Research (CDR) Ltd and the Avon Longitudinal Study of Parents And Children (ALSPAC) involved the measurement of attention in ALSPAC participants using the laptop-based CDR computerised assessment system. This collaboration was to be based around our generic collaboration agreement, a copy of which is attached, but owing to oversights, was not signed for this particular data gathering exercise.

The central dataset we use at CDR will include the CDR variables collected, and require demographic information from the ALSPAC study (gender and age required; handedness and race if available).

In keeping with the spirit of the standard CDR Collaborative Research Programme agreement (example attached), it is proposed that both parties have shared access to the data by holding identical copies.

Intended use

CDR hold a large in-house normative database of cognitive data. We propose to add the ALSPAC data to this database. Data will be anonymised, and reference to the source of the data in relation to our norms will not be made. The CDR normative database is used internally for reference and not published or sold externally.

Publication

If publication or presentation of the work occurs, both CDR and the Collaborating Group must agree the content of the publication or presentation. The 'Cognitive Drug Research computerised assessment system' must be mentioned in any publication or presentation. Representatives from both CDR and the Collaborating Group must be on the author list of any publication or presentation.

The publication policy of the ALSPAC study will be adhered to.

Generally, with any publications or conference presentations, the ALSPAC will take senior authorship, and one or more members of the CDR team who has been involved in the research will receive junior authorship.

If there are any questions relating to this proposal, Paul Snell would be happy to address them in the first instance.

Date proposal received: 
Friday, 27 June, 2008
Date proposal approved: 
Friday, 27 June, 2008
Keywords: 
Primary keyword: 

B668 - Adiponectin as a biomarker in pharmacoepidemiology and as a biomarker in the wide human clinical phenome - 26/06/2008

B number: 
B668
Principal applicant name: 
Prof Ian Day (University of Bristol, UK)
Co-applicants: 
Prof Lyle Palmer (Not used 0, Not used 0), Vilmundur Gudnason (Not used 0, Not used 0), Shah Ebrahim (Not used 0, Not used 0), John Beilby (Not used 0, Not used 0), Prof George Davey Smith (University of Bristol, UK), Prof Craig Pennell (Not used 0, Not used 0), Prof Yaov Ben-Schlomo (University of Bristol, UK), Prof Debbie A Lawlor (University of Bristol, UK), Dr Nic Timpson (University of Bristol, UK), Santiago Rodriguez (University of Bristol, UK), Prof Naveed Sattar (University of Glasgow, UK), Dr Susan Ring (University of Bristol, UK)
Title of project: 
Adiponectin as a biomarker in pharmacoepidemiology; and as a biomarker in the wide human clinical phenome
Proposal summary: 

Adiponectin is the most highly expressed adipocyte protein and is readily measurable in serum. It

has been extensively studied in the context of obesity, diabetes and metabolic syndrome and has

been clearly shown to have a direct role in the pathogenesis of diabetes. Being negatively

correlated with fat mass and acting as an insulin sensitizer, it represents one critical link between

fat mass and diabetes. It also has directly anti-inflammatory actions. Vascular disease and other

consequences of diabetes are among the most major diseases of our era in the developed and

developing worlds. This then states the general prominence of the protein. This proposal concerns

the biomarker potentials of adiponectin ranging beyond its pathogenic role in diabetes. We focus

on its potential as a pharmacoepidemiological marker and on its relationships to many other

facets of the clinical phenome.

Date proposal received: 
Thursday, 26 June, 2008
Date proposal approved: 
Thursday, 26 June, 2008
Keywords: 
Genetics
Primary keyword: 

B665 - The Epidemiology of Balance Problems in Childhood the affect of alcohol consumption during pregnancy - 26/06/2008

B number: 
B665
Principal applicant name: 
Rachel Humphriss (Not used 0, Not used 0)
Co-applicants: 
Title of project: 
The Epidemiology of Balance Problems in Childhood: the affect of alcohol consumption during pregnancy.
Proposal summary: 

05.07.2010

E-mail from Rachel - 5/7/10

I'm doing this project for my PhD - have done nearly three years, another 12 - 18 months to go I think. I've had one paper rejected, and am about to send the exec a new version. Another paper is also nearly ready for the exec.

Date proposal received: 
Thursday, 26 June, 2008
Date proposal approved: 
Thursday, 26 June, 2008
Keywords: 
Alcohol
Primary keyword: 

B667 - Long-Term Outcomes of Information Processing in Infancy - 25/06/2008

B number: 
B667
Principal applicant name: 
Prof Mark H Bornstein (National Institute of Health & Human Development, , USA)
Co-applicants: 
Prof Dieter Wolke (Not used 0, Not used 0), Dr Chun Shin Hahn (Not used 0, Not used 0)
Title of project: 
Long-Term Outcomes of Information Processing in Infancy
Proposal summary: 

Long-Term Outcomes of Information Processing in Infancy

(From data on "Children in Focus")

From data on "Children in Focus" collected from 4 months to 11 years, we aim to investigate the following research questions:

Prediction from habituation to later information processing/memory as well as to attention measures.

Prediction from habituation to later cognitive tests and language /speech.

Stability of information processing and short term memory tasks.

Stability of IQ/cognitive tests.

Stability of Language/Speech.

Stability of individual differences in children's performance across age will be evaluated by Pearson correlation coefficients. To assess the predictive validity of habituation on later child outcomes, structural equation modeling will be conducted to obtain both direct and indirect effects as well as take into consideration a variety of control variables. To increase the precision of the within-child cognitive stability findings and to obtain the unique predictve validity of infant habituation on childhood outcomes, we will take into consideration (as we have done previously) child temperament, gender, birth-order, maternal education, and home environment.

Date proposal received: 
Wednesday, 25 June, 2008
Date proposal approved: 
Wednesday, 25 June, 2008
Keywords: 
ADHD, Antisocial Behaviour, Behavioural Problems
Primary keyword: 

B666 - Using Lifecourse analyses to predict axial length changes and myopia in the ALSPAC cohort - 25/06/2008

B number: 
B666
Principal applicant name: 
Miss Cathy E M Williams (University of Bristol, UK)
Co-applicants: 
John Sparrow (University of Bristol, UK), Dr Clare Gilbert (Not used 0, Not used 0), Dr Jez Guggenheim (University of Cardiff, UK), Prof Bianca De Stavola (Not used 0, Not used 0)
Title of project: 
Using Lifecourse analyses to predict axial length changes and myopia in the ALSPAC cohort
Proposal summary: 

Study Plan

In this 3-year study, the named applicant (SS) will spend 2 years working on life course models to develop and test causal pathways for myopia using the 15-year data. At the same time, data on myopic progression will be collected from cohort members who attend the 17+ clinic (estimated as 4,500?). In the third and final year, the most robust models derived from years 1 and 2 will be used to analyze the newly acquired myopia progression data (i.e. change in axial length). Outputs will include papers on both the methodologies employed, with recommendations for use in other contexts and on the predictive power of eye growth over the lifecourse analyses to predict myopia.

Date proposal received: 
Wednesday, 25 June, 2008
Date proposal approved: 
Wednesday, 25 June, 2008
Keywords: 
Development, Neurology, Vision, Moto Co-ordination
Primary keyword: 

B669 - A replication of Jacobusse et als Rasch model for child development - 23/06/2008

B number: 
B669
Principal applicant name: 
Dr Jon Heron (University of Bristol, UK)
Co-applicants: 
Dr Tim Croudace (University of Cambridge, UK)
Title of project: 
A replication of Jacobusse et al's Rasch model for child development
Proposal summary: 

No outlined received

Date proposal received: 
Monday, 23 June, 2008
Date proposal approved: 
Monday, 23 June, 2008
Keywords: 
ADHD, Antisocial Behaviour, Behavioural Problems
Primary keyword: 

B670 - A combinatorial approach using steroidogenic factor 1 SF-1 NR5A1 to elucidate novel mechanisms in human biology - 16/06/2008

B number: 
B670
Principal applicant name: 
Dr John Achermann (UCL Institute of Child Health, London, UK)
Co-applicants: 
Prof Peter Hindmarsh (UCL Institute of Child Health, London, UK), Prof Steve Humphries (UCL Institute of Child Health, London, UK)
Title of project: 
A combinatorial approach using steroidogenic factor 1 (SF-1, NR5A1) to elucidate novel mechanisms in human biology
Proposal summary: 

BACKGROUND

Steroidogenic factor-1 (SF1, NR5A1) is a nuclear receptor that plays a central role in many aspects of adrenal, reproductive and metabolic function. Deletion of Sf1 (FtzF1) in mice causes adrenal and gonadal agenesis, and several loss of function mutations in SF1 have now been reported in humans with adrenal dysfunction and/or disorders of sex development. In addition to these well-established effects, Sf1 is also emerging as an important regulator of ventromedial hypothalamic development and programming, and post-natal obesity has been reported in Sf1 knock-out mice rescued by adrenal transplantation (1, 2). Although incidental reports of weight changes in patients with SF1 mutations exist, corticosteroid administration may have influenced growth in some cases, so the true role of SF1 in humans is still poorly understood.

Recent work has shown that a non-synonymous polymorphism exists in the coding sequence of SF1 (p.G146A, rs1110061) (3, 4). Studies in our laboratory have shown that this change does not affect nuclear localization or cellular dynamics, but does result in a mild but potentially significant effect on SF1 function in the transcriptional regulation of a range of target genes. In additional limited studies published recently, this polymorphim has been shown to be associated with undescended testes or micropenis in two small cohort studies in Japan (5, 6), and with an increased incidence of type 2 diabetes mellitus in the Chinese (7).

We have now undertaken analysis of this p.G146A polymorphism in SF1 in a UK-based cohort of mothers and children in the UCL Fetal Growth Study (Professor Peter Hindmarsh). This polymorphism is present in heterozygous state in approximately 8% of the 460 children studied and is in Hardy-Weinberg equilibrium. Heterozygosity for p.G146A was associated with a reduction in placental weight (643g vs 678g, pless than 0.05) and preterm delivery (15.3% vs 4.3%; Chi-square, 7.4; p=0.02; OR 0.25, 95% CI 0.09-0.77). Although there was no significant difference in birth weight between groups, analysis of post-natal growth data in a subset of children showed that a heterozygous p.G146A polymorphism was associated with higher BMI at three years of age (17.8 kg/m2 vs 16.3 kg/m2, pless than 0.001) and a significant elevation in both systolic and diastolic blood pressure.

We are therefore interested in establishing whether these findings can be reproduced in an independent population based cohort of children in the UK. It would also be of great interest to see if an association with undescended testes or hypospadias could be seen in the UK population, although it is possible that this would be underpowered and a case-control approach would be better.

AIM

We would aim to collaborate with K biosciences to establish the SF1 polymorphism (p.G146A, G/C, rs1110061) genotype status in the ALSPAC cohort. We would agree that genetyping the entire cohort would have potential added value in the long term, and would support this approach depending on cost implications. Taqman SNP genotyping probes for this change have been obtained from ABI and validated by Professor Steve Humphries at UCL for the study of an adult cohort, thus I would assume that K biosciences would be able proceed with this project without unexpected difficulties.

Date proposal received: 
Monday, 16 June, 2008
Date proposal approved: 
Monday, 16 June, 2008
Keywords: 
Genetics
Primary keyword: 

B663 - Does a variant in the ADH1B gene predict alcohol intake - 12/06/2008

B number: 
B663
Principal applicant name: 
Ms Luisa Zuccolo (University of Bristol, UK)
Co-applicants: 
Prof George Davey Smith (University of Bristol, UK)
Title of project: 
Does a variant in the ADH1B gene predict alcohol intake?
Proposal summary: 

To date, no common genetic variant is known to be associated with levels of alcohol intake in populations of European ancestry. We have identified one genetic variant in one of the genes involved in alcohol metabolism (ADH1B), which predicts alcohol intake in a cohort of 50-70 year old British men of white ethnic origin (N=4000). The minor allele frequency in Europeans ranges between 1% and 3%. This variant has recently been reported to be highly protective of aerodigestive tract cancers in a pooled analysis of 5 cohorts, with a more marked effect among heavy drinkers compared to moderate drinkers, and no evidence of an effect in lifelong teetotallers, suggesting the effect is purely due to a gene-environment interaction (1). In laboratory experiments, individuals with at least one copy of the variant have been shown to metabolise ethanol 100 times faster than those with two copies of the common allele (2).

ADH1B has three alleles - ADH1B*1 is 47Arg and 369Arg (common allele, common SNPs at both sites), ADH1B*2 is 47His and 369Arg (variant at site rs1229984 and common at site rs2066702), ADH1B*3 is 47Arg and 369Cys (common and variant, respectively, not found among Europeans). According to Osier (3), the double variant is in theory possible but has not been observed. The ADH1B*2 (almost fully captured by the SNP rs1229984) is the variant associated with protective effect for alcoholism (the His variant is the fast metabolizer, resulting in much higher levels of acetaldehyde). Although this has been observed e.g. among Jewish university students in the US who exhibited higher alcohol elimination rates (His/His greater than Arg/His greater than Arg/Arg) (4), environmental factors (e.g. social setting) have been shown to account for more marked differences in frequency and amount of drinking than ADH1B genotypes (5), with students drinking considerably more than other adults from the Jewish community.

There have been many speculations about selection operating on ADH1B*47His allele in East Asia (see, for example, (6)), Han conducted a comprehensive study of 54 SNPs in 42 populations on the ADH cluster, finding the first evidence of selection for the locus but doubting its link to the 'modern' phenotype of alcoholism (7). However, among Irish and Danish, no variation was observed at site ADH1B Arg47His (rs1229984), nor at rs28626993 (intron3) (see Han et al (7)).

There are inconsistencies in the literature that cannot confirm a clear effect of the rare variant of this SNP on alcohol intake in Caucasian populations, mainly due to lack of power. We have recently investigated the association between the ADH1B variant rs1229984 and alcohol consumption in approximately 4000 middle-aged British men who attended prostate cancer screening. This is a case-control study nested in cohort from the ProtecT study, and alcohol consumption in these men is significantly varied, with many classified as heavy drinkers. Excluding men of ethnicity different from 'white', we noted that the presence of the rare allele for this SNP was associated with lower alcohol consumption. Notably our results would be consistent with the gene-environment interaction effect reported by Hashibe and colleagues (1), however no direct data on alcohol intake are available for a formal comparison.

Given the initial evidence that this SNP is associated with alcohol drinking in men with such high levels of the phenotype (alcohol drinking), we aim at replicating such findings in ALSPAC using genotype and alcohol data collected from the mothers during several times in their life, which we expect to be reflecting on average lower intakes, and to be of better quality (smaller measurement error).

Concept * Specific Measure * Person * Source * Time

Alcohol intake * self-reported alcohol intake * Mother * Questionnaire * ALL

(markers) * smoking * Mother * " * ALL

* socio-economic status variables * " * " * "

* height, weight * " * " * "

Date proposal received: 
Thursday, 12 June, 2008
Date proposal approved: 
Thursday, 12 June, 2008
Keywords: 
Alcohol, Genes
Primary keyword: 

B664 - Comparison of dietary patterns in under-reporters vs valid reporters and 24h recall vs diet diaries - 09/06/2008

B number: 
B664
Principal applicant name: 
Dr Kate Northstone (University of Bristol, UK)
Co-applicants: 
Vicky Cribb (Not used 0, Not used 0), Dr Pauline Emmett (University of Bristol, UK), Mrs Louise R Jones (University of Bristol, UK)
Title of project: 
Comparison of dietary patterns in under-reporters vs valid reporters and 24h recall vs diet diaries
Proposal summary: 

We have recently shown in the ALSPAC cohort that differences are evident in food and nutrient intakes at 10 and 13 years in those young people classified as under-reporters compared to those with valid reports. Similarly, differences are evident in those completing 2/3 dietary diaries compared to 24 hour recall (papers in progress).

Following on from my PhD work, I would like to investigate any differences in dietary patterns obtained using Principal Components Analysis (PCA) and cluster analysis in these groups. To my knowledge this has not been investigated by any other studies and will therefore make a significant contribution to the literature on dietary patterns. This work will also feed into the analyses that we hope to carry out should our NIH application (dietary patterns and changes in body fat) be successful.

Date proposal received: 
Monday, 9 June, 2008
Date proposal approved: 
Monday, 9 June, 2008
Keywords: 
Diet, Eating Disorder, Weight
Primary keyword: 

B661 - Does a common variant in the Per2 gene predict alcohol intake and sleeping patterns - 05/06/2008

B number: 
B661
Principal applicant name: 
Ms Luisa Zuccolo (University of Bristol, UK)
Co-applicants: 
Prof George Davey Smith (University of Bristol, UK)
Title of project: 
Does a common variant in the Per2 gene predict alcohol intake and sleeping patterns?
Proposal summary: 

Daily and seasonal rhythms in the endocrine system are co-ordinated by a hypothalamic pacemaker, the suprachiasmatic nuclei (SCN) that is synchronised to solar time by inputs from the eyes. The SCN neurons act as circadian clocks and incorporate Period (Per) and Cryptochrome (Cry) genes. Mutations that alter the rate of transcription of Per and Cry genes or the stability of Per and Cry proteins affect clock speed 1. In Framingham off-spring study, clock variants have been associated with time of going to bed, sleepiness and sleep duration 2. There is also evidence of a role for clock variants in major depressive illness (where sleep disturbance is a feature), seasonal affective disorder (winter depression) 3, bipolar mental illness but little evidence for anxiety states 4.

Alcohol consumption has been shown to be linked to altered circadian rhythmicity in a complex bidirectional way. On one hand, animal studies suggest that "fetal exposure to ethanol significantly alters the clock mechanism governing the circadian function of beta-endorphin neurons"5, and increased drinking in adulthood has been suggested as a consequence of night-shift work 6 or severe jet lag 7. On the other hand, Spanagel et al published evidence on mPer2 mutant mice presenting increased consumption of self-administered ethanol, which was supported by a study among 215 patients with confirmed alcohol dependence 8. The effect seems to be specific to Per2, as no evidence was found for a differential ethanol reinforcement, seeking, or relapse behaviour in mPer1-mutant mice, compared to the wild type 9. Moreover, alterations of glutamatergic components resulted from deletion of mPer2 8 but not mPer1 9. The evidence on efficacy of acamprosate for relapse prevention in alcoholics 10, 11 and mPer2 mutant mice 8 supports a direct effect of hyperglutamatergic states in the brain on alcohol addiction. A haplotype composed of 4 SNPs (including the rare allele of the proposed SNP rs2304674) was found to be associated with lower alcohol consumption among Western European alcoholics (less than 300 g/d compared to (cubed)300 g/d), with one SNP in the haplotype possibly regulating transcriptional activation of Per2 8. However it is not clear whether the differential ethanol intake in mPer2 mutant mice and in the patients with the lower alcohol consumption haplotype was specifically due to altered circadian rhythmicity 12.

No further published evidence is available to date to confirm these findings in humans. We have recently investigated the association between Per2 variants rs56013895 and rs2304674 (two of those in Spanagel's paper 8) and alcohol consumption in the British Women Heart and Health Study (BWHHS). This is a cohort of British women aged 60-80 years, whose alcohol consumption is remarkably low. Excluding women of ethnicity different from 'white', we noted that the presence of the rare allele for the latter SNP was associated with lower alcohol consumption, and the effect was more pronounced for rare allele homozygotes Vs heterozygotes. Notably our results are in the same direction as those reported in 8, but are based on a population sample characterised by extremely different phenotype (moderate drinkers Vs alcoholics). This variant is common among Europeans (HapMap CEU minor allele frequency: 0.233). The other SNP (rs56013895) showed similar results, but is much more rare.

Given the initial evidence that this SNP is associated with alcohol drinking in groups with such different levels of the phenotype, we aim at replicating such findings in ALSPAC using genotype and alcohol data collected from the mothers. Moreover, since variations in hPer2 gene have been linked to morning preference and/or sleeping patterns, we will analyse independently offspring genotype in relation to detailed sleep data in the children.

Date proposal received: 
Thursday, 5 June, 2008
Date proposal approved: 
Thursday, 5 June, 2008
Keywords: 
Alcohol, Genetics, Sleep Patterns
Primary keyword: 

B660 - Genes and mediating mechanisms in childhood ADHD - 03/06/2008

B number: 
B660
Principal applicant name: 
(University of Cardiff, UK)
Co-applicants: 
Dr Jon Heron (University of Bristol, UK), Dr Carol Joinson (University of Bristol, UK), Dr Kate Langley (University of Cardiff, UK)
Title of project: 
Genes and mediating mechanisms in childhood ADHD.
Proposal summary: 

Attention Deficit Hyperactivity Disorder (ADHD) is a common, extremely disabling disorder that has major adverse sequelae in childhood and later life. Despite being such an important clinical problem, the aetiology and pathogenesis of ADHD is poorly understood. The available evidence shows that genetic factors are of major importance and that genes co-act and interact with environmental risk factors. The presence of antisocial behaviour in children with ADHD is an important marker of heterogeneity, indexing greater clinical severity, poorer outcome, persistent problems in adult life, a stronger association with neurocognitive deficits, especially affecting prefrontal cortical functioning and higher genetic loading.

Previous evidence had suggested that prefrontal cortical function is influenced by a valine/methionine variant in the catechol-O-methyltransferase (COMT) gene and indeed this was recently found in the ALSPAC sample (Barnett et al., 2007). We tested for association between this functional COMT gene variant and antisocial behaviour in ADHD in our well characterised sample of 240 clinic children with ADHD. We found evidence of association with the same COMT val/val genotype (Thapar et al, 2005). Since this publication, the finding has been replicated in two independent population-based samples (Caspi et al, 2008). There was significant evidence of association between the COMT val/val genotype and 1) childhood antisocial behaviour in those with ADHD in one sample, and 2) adult criminality in those with ADHD in the other. A pooled analysis of 4 published studies, showed significant association (Caspi et al, 2008).

The aim of this first stage proposal is to identify a potential mediating mechanism. Specifically we wish to test the hypothesis that

1). the COMT val/val genotype is associatied with antisocial behaviour in ADHD and

2). these effects are mediated through prefrontal cortical functioning.

The aim at this stage is to undertake analysis on existing data, develop research links with Bristol under the auspices of the Neurosciences Centres, publish findings and provide the basis for a subsequent grant /fellowship application.

The future application would aim to integrate the research we are undertaking on a clinical sample through Wellcome Trust programme funding on the genetics of ADHD with ALSPAC data. The key aims would be to test associated gene variants (gene discovery in other samples-notably our own clinical study and collaborative whole genome association studies) in a population-based sample a)for links with ADHD and antisocial behaviour in ADHD and b)investigate potential mediating mechanisms-specifically cognitive vs. emotion-based pathways.

Date proposal received: 
Tuesday, 3 June, 2008
Date proposal approved: 
Tuesday, 3 June, 2008
Keywords: 
ADHD, Genes, Genetics
Primary keyword: 

B659 - Obesity and depression in adolescents linked to B799 - 30/05/2008

B number: 
B659
Principal applicant name: 
Dr Nicola Wiles (University of Bristol, UK)
Co-applicants: 
Prof Glyn Lewis (University of Bristol, UK), Prof Debbie A Lawlor (University of Bristol, UK), Prof Andy Ness (University of Bristol, UK), Prof Kate Tilling (University of Bristol, UK), Dr Jon Heron (University of Bristol, UK)
Title of project: 
Obesity and depression in adolescents (linked to B799).
Proposal summary: 

Specific Objectives

(1) To determine whether obese adolescents have an increased risk of depression 2 to 6 years later

(2) To determine whether depressed adolescents are more likely to become obese 2 to 6 years later

(3) To examine the inter-relationship between obesity and depression amongst adolescents aged 9 to 15/16 years.

Date proposal received: 
Friday, 30 May, 2008
Date proposal approved: 
Friday, 30 May, 2008
Keywords: 
Depression, Obesity
Primary keyword: 

B655 - Replication studies of hypertension genes - 29/05/2008

B number: 
B655
Principal applicant name: 
Prof Mark Caulfield (Barts and London School of Medicine, UK)
Co-applicants: 
Patricia Munroe (Not used 0, Not used 0), Martin Farrall (Not used 0, Not used 0), David Clayton (Not used 0, Not used 0), Maurice Brown (Not used 0, Not used 0), Anna Dominiczak (Not used 0, Not used 0), John Connell (Not used 0, Not used 0), Nilesh Samani (Not used 0, Not used 0), Mark Lathrop (Not used 0, Not used 0), John Webster (Not used 0, Not used 0)
Title of project: 
Replication studies of hypertension genes
Proposal summary: 

Background

There are over 1 billion people with high blood pressure worldwide and simulations by the World Health Organisation suggest this will rise to 1.5 billion by 2020 [1]. It is estimated that blood pressure played an important part in 50% of the 16.7M cardiovascular deaths worldwide [1, 2]. In spite of the availability of multiple different therapeutic strategies, public health data from western economies shows hypertension remains poorly controlled.

The Wellcome Trust Case Control Consortium and replication of signals

In the first phase of WTCCC 2000 hypertensives from the BRIGHT Study were subjected to a genomewide scan using the Affymetrix 500 chip and compared with 3000 common controls. We found comparable numbers and distribution of suggestive association signals in the range P less than 10-4 to 10-7 compared with the 6 other diseases investigated [3]. We are actively pursuing the most promising signals from WTCCC1 and parrallel candidate gene studies in extended replication resources and have waited to approach ALSPAC until we had evidence that some of these signals had survived initial replication with blood pressure and hypertension with decreasing P values. We have also found association of SLC2A9 SNPS with urate and a borderline association with blood pressure. In a second candidate gene we have found a developmental gene that influences nephron number to relate to blood pressure. ALSPAC represents and ideal resource for evaluation of these putative associations.

Reasons for approaching ALSPAC now.

Our reasons for approaching ALSPAC childrens DNA bank now is to investigate association of these variants with early life blood pressure ( at all time points you have these measures) and flow mediated dilatation as a measure of endothelial function (at all time points). In at least 2 cases the genes are implicated in nephron development which makes investigation of early life association of blood pressure valuable. One of these genes might also be involved in control of birthweight ( testing association with measures of birth weight and anthropometry might be interesting). If there was access to renal function measures such as eGFR or urea and creatinine we would also be interested in these but we think from what we can tell these may not be available. We would be happy to receive advice on any other phenotypes you think we should test.

Genotyping at KBioscience and funding.

We provide below a list of SNPs for genotyping on fast-turn around at K Bioscience and will fund this work from our MRC Programme.

Date proposal received: 
Thursday, 29 May, 2008
Date proposal approved: 
Thursday, 29 May, 2008
Keywords: 
Genetics
Primary keyword: 

B656 - Cardiorespiratory outcomes in preterm infants - 23/05/2008

B number: 
B656
Principal applicant name: 
Prof Sailesh Kotecha (University of Cardiff, UK)
Co-applicants: 
Dr Silvia Paracchini (Wellcome Trust Centre for Human Genetics, UK), Diane Newbury (Not used 0, Not used 0)
Title of project: 
Cardiorespiratory outcomes in preterm infants
Proposal summary: 

AIMS

We wish to address three questions using the ALSPAC data:

AIM ONE:

We hypothesise that IUGR has a greater effect on lung function abnormalities then prematurity alone. We wish to identify children who were born prematurely (less than =37 weeks gestation) and who did or did not have IUGR (birthweight less than 10%) and compare results for lung function (especially FEV1.0, FVC, FEFs) to determine if growth retardation has a greater effect on lung function abnormalities then prematurity alone. Lung function data from term infants will be used as a reference population. The data will be sub-divided into different gestation ranges (24 - 28 weeks, 29 - 32 weeks, and 33 - 36 weeks). Multiple logistic regression analyses will be used to address this question.

AIM TWO:

We hypothesise that catch up growth is associated with better lung function parameters obtained at school age. The growth of infants (born at less than 37 weeks gestation) who had IUGR at birth will be assess and divided into catch up growth (defined as crossing at least two percentile compared to birth weight) and those who remain growth retarded. The lung function parameters at school age will be compared between these two groups with and without catch up growth.

AIM THREE:

The relationship between lung function abnormalities and early development of cardiac disease clearly remains of interest. We are aware of the need for the investigators to use the recently acquired arterial stiffness data for their own studies but in collaboration with John Deanfield's group, we wish to investigate the links between lung function abnormalities and arterial stiffness. We wish to look at both children who were born prematurely (less than 37 weeks divided gestations as above) and those who were born at term (greater than =37 weeks) and compare the arterial stiffness data with abnormalities of lung function (as above especially FEV1.0, FVC and FEF) to determine if lung function abnormalities in childhood are already associated with developmetn of arterial stiffness in early childhood.

We wish to address these three questions in conjunction with the local team especially with Dr John Henderson and with John Deanfield who is a colleague of our recently appointed Professor of Cardiology, Professor Julian Holcox).

Date proposal received: 
Friday, 23 May, 2008
Date proposal approved: 
Friday, 23 May, 2008
Keywords: 
Allergies, Respiratory, Atopy
Primary keyword: 

B657 - Evaluating the utility of liver enzymes as biomarkers for non-alcoholic fatty liver disease in adolescents - 22/05/2008

B number: 
B657
Principal applicant name: 
Prof Debbie A Lawlor (Not used 0, Not used 0)
Co-applicants: 
Prof Chris Day (University of Newcastle, ROW), Prof Naveed Sattar (University of Glasgow, UK), Dr Marl Callaway (Not used 0, Not used 0), Dr Abigail Fraser (University of Bristol, UK)
Title of project: 
Evaluating the utility of liver enzymes as biomarkers for non-alcoholic fatty liver disease in adolescents
Proposal summary: 

Background

Non-alcoholic fatty liver disease (NAFLD) is defined as fatty infiltration of the liver in the absence of alcohol misuse or other causes of liver damage and is probably the most common liver disorder in all ages in the developed world today. NAFLD includes a wide spectrum of liver damage, ranging from simple steatosis to advanced fibrosis and cirrhosis (this advanced form referred to as non-alcoholic steatohepetitis (NASH)). The primary cause of NAFLD is obesity and with the global epidemic of obesity the prevalence of NAFLD and its complications are increasing. NAFLD has recently been described as "a disease of our generation", as clinicians have noted a large increase in liver pathology in all ages driven by the obesity epidemic, in addition to increasing rates of alcohol consumption.

The whole spectrum of NAFLD has been described in children and adolescents. Presentation with, and progression to, cirrhosis in adolescence has also been described. Estimates of the prevalence of NAFLD, based on unexplained elevated levels of alanine aminotransferase (ALT) or USS, range from 2-3% in general paediatric populations, to between 10-30% in obese children or adolescents. These studies suggest that NAFLD is rare before adolescence, findings confirmed in a recent post-mortem study that provides the most robust evidence of the potential importance of NAFLD in adolescents. In that study, of 742 US individuals (aged 2-19 years) who had died from external causes (mostly road traffic accidents) the age, gender and ethnicity standardised prevalence of NAFLD (defined as greater than 5% steatosis on histology of the post-mortem liver) was 9.6%, with 3% of the population having NASH. The prevalence increased with increasing age from 0.7% in those ages 2-4 to 17.3% in those aged 15-19; it was very rare before the age of 10. Of importance, as duration of NAFLD in adults is associated with increased likelihood of progression to severe advanced disease, this means that it is likely that individuals with NAFLD in adolescence are at a very high risk of severe liver pathology in adulthood if fatty infiltration of their liver is not reversed (since by definition having the condition from adolescence into adulthood is a longer duration than fatty infiltration first appearing in adulthood). In one small (N=9) case study of clinically obese children who were referred because of persistently elevated ALT levels, those who complied with a hypocaloric diet were reported as having reductions in ALT levels that paralleled their weight loss. However, stronger epidemiological evidence is required to determine whether evidence of NAFLD in early life is reversible or whether changes in risk factors in early life can reverse evidence of hepatic fatty infiltration, liver damage and its associated adverse metabolic and vascular traits.

We recently found that 6% of a general (healthy) population of white American adolescents (age 12-19 years) had elevated ALT levels indicative of NAFLD (using a threshold of greater than =30 U/L to define NALFD). Furthermore, we showed marked differences in the distribution of ALT by gender (age standardised mean levels lower in girls compared with boys even after adjustment for body mass index (BMI)), which raises the question as to whether the same threshold of defining NAFLD in this age group should be used. We also found mean levels varied by ethnicity and that overtime mean ALT levels in adolescence have increased in this population. We used the publicly available US National Health and Nutrition Examination Survey (NHANES), which is an annually repeated cross-sectional survey that is used for public health surveillance and epidemiological studies in the US. Similar surveys - the Health Survey for England, the Scottish Health Survey and the Welsh Health Survey (http://www.natcen.ac.uk/natcen/pages/or_health.htm) - exist in the UK and are similarly used for public health surveillance and epidemiological studies. We sought to undertake a study of prevalence of elevated ALT and variation in ALT by gender, ethnicity and over time in adolescents in the UK but found that our national surveys did not have information on biomarkers for NAFLD. The lack of such data can be justified because, despite our and others attempts to examine the prevalence of NAFLD in adolescents using liver enzymes as biomarkers, there is currently insufficient evidence evaluating the utility of liver enzymes as biomarkers for NAFLD in adolescents in general or in the UK adolescent population in particular. Liver enzymes are relatively cheap and easy to assay. They would, therefore, be ideal for public health surveillance if they are shown to be accurate as diagnostic biomarkers in adolescents.

The diagnosis of NAFLD is suspected when there are indicative changes in liver enzymes (ALT, aspartate aminotransferase (AST), ALT:AST) and/or echogenic (fatty) liver detected by USS, together with the absence of any established causes of liver disease. A definitive diagnosis, and determination of severity, requires a liver biopsy, which is not feasible in large-scale epidemiological studies. Indeed, since liver biopsies are painful and have rare, but potentially severe, iatrogenic effects even in clinical practice liver biopsy is only recommended when there is a high level of suspicion of liver damage and clear indications that biopsy would alter clinical practice. The British Society of Gastroenterology and the British Association for the Study of the Liver guidelines for the use of liver biopsy in clinical practice state that the role of liver biopsy in the diagnosis and clinical management of NAFLD is currently not established. Similarly the American Gastroenterology Association have noted that the potential health risks, high cost and biopsy sampling errors associated with liver biopsy should be weighted against the value of the information that would be gained from performing a biopsy each patient. In clinical practice a combination of clinical history, measures of adiposity, presence of other associated morbidities, such as diabetes, elevated aminotransferases (ALT, AST and ALT:AST) and imaging modalities (USS, CT scan and MRI) are used and recommended in clinical guidelines for the diagnosis of NAFLD.

In research, elevated aminotransferases (ALT, AST, ALT:AST) have been predominantly used for case definition of NAFLD. However, there is marked variation in the thresholds used to define NAFLD across different studies, even when the same or very similar populations are used. For example, three studies have used ALT to assess NAFLD prevalence in adults from the USA NHANES survey and have used different thresholds - 19, 31 or 43 u/L in women; 40 or 43 u/L in men. Far fewer studies have examined the prevalence of NAFLD in general adolescent populations, but similar variation is found. ALT thresholds of between 30-40 u/L have been use, with identical thresholds used in females and males, despite clear evidence that in adolescence (as in adulthood) the distribution of ALT varies by gender.

There is biological plausibility for all three of ALT, AST and GGT as biomarkers for NAFLD; all are secreted by hepatocytes in response to liver damage, including NAFLD. ALT is the liver enzyme most commonly used in the assessment of liver conditions in general, including NAFLD, though its primary use has been questioned. It is a more specific marker of liver damage than AST, which is also found in the heart, skeletal muscle, kidney and other organs, and than GGT, which is expressed by most cells in humans. ALT elevation is greater than AST elevation in NAFLD and ALT is a more robust predictor of diabetes. Nonetheless elevation in both aminotransferases, ALT and AST, are recommended in clinical guidelines as biomarkers for NAFLD in adults. In NAFLD, plasma levels of both ALT and AST may be increased due to leakage from hepatocytes that have been damaged by fat accumulation. In addition, as ALT has an important role in gluconeogenesis and amino acid metabolism its greater elevation (compared to AST) may reflect increased gluconeogenesis, due to hepatic insulin resistance that is closely associated with liver fat accumulation, in addition to leakage from hepatocytes. Because of the greater ALT compared to AST elevation with NAFLD a low (below 1) AST:ALT ratio has also been suggested as a valid biomarker for NAFLD. The low AST:ALT ratio contrasts to the high (above 1) AST:ALT ratio that is typical of alcoholic liver disease.

GGT levels also increase with NAFLD, although this enzyme is not mentioned in clinical guidelines as part of the screening or diagnostic procedures for NAFLD. This is probably because it is has long been used as a marker of alcohol consumption and because it is expressed in most cell types and is therefore not a liver specific enzyme. In NAFLD, leakage from damaged hepatocytes would explain elevated levels of GGT. Thus elevated GGT levels could equally represent excess alcohol intake or NAFLD. Few adolescents are likely to have experienced the chronic alcohol abuse that is required to cause liver damage. Thus, it is biologically plausible that in adolescents GGT is also a useful biomarker for NAFLD. In this application we will use genetic variants associated with greater fat mass as proxies for fat related increase in GGT, and other enzymes (i.e. NAFLD related enzyme increase). These genetic variants are not associated with alcohol consumption and therefore we are able to use them to examine the extent to which elevated GGT, ALT and AST might be explained by NAFLD as opposed to alcohol consumption or other non-fat causes of liver damage.

Few studies have formally evaluated the utility of ALT, AST, AST:ALT and GGT as biomarkers for NAFLD in adolescents. One study in adults with the more severe form of NAFLD (non-alcoholic steatohepetitis (NASH)) examined the utility of ALT and AST as biomarkers for treatment effects in randomised controlled trials. The motivation of the investigators was their recognition of the need for relatively cheap and non-invasive surrogates even in RCTs of adults with more advanced disease (in whom biopsy would be more likely that in public health / epidemiological studies or trials of preventive interventions in health adolescents). Within a subgroup (N=102) in the trial they compared changes in ALT and AST levels to the main outcomes assessed by liver biopsy. They concluded that both aminotransferases were equally useful in RCTs of treatment for NASH in adults. Utility (assessed by receiver-operating characteristic (ROC) curves) was improved in multivariable analyses that adjusted for baseline ALT and AST levels as well as histological changes obtained from liver biopsy at baseline. In children and adolescents it has been suggested that elevated ALT levels potentially miss up to 40% of individuals with NAFLD.5;31These statements have been made largely on the basis of comparisons of elevated ALT with liver biopsy in clinical obese paediatric populations, who are unlikely to be representative of general populations. Even within clinically obese paediatric populations there are inconsistencies in the findings. For example, one study of obese Japanese children (up to age 16) found that a threshold of 30 u/L of ALT had a sensitivity of 0.92 (i.e. identified 92% of cases) for detecting NAFLD proven by USS. That study tested a particular threshold rather than using ROC curves33 to identify a threshold that maximises both sensitivity and specificity.

Thus, to date, there has been no thorough evaluation of ALT, AST, AST:ALT and GGT as biomarkers for NAFLD in general populations of adolescents. If we find that ALT, AST and GGT either alone or in combination are valid biomarkers for NAFLD they will provide a cheap and easily available marker that could be used widely for public health surveillance, epidemiological research and randomised controlled trials of preventive interventions.

In a healthy liver there should be no or very little fatty infiltration. The formal definition of NAFLD is that just 5% (or more) of hepatocytes have fatty infiltration on biopsy. On USS fat appears as a bright area. The USS indicators of fatty infiltration in the liver are bright hepatic echotexture (compared to the kidneys and/or spleen), deep attenuation and vascular blunting, and the extent of fatty infiltration can be quantified (none, mild, moderate and severe), with this quantification also shown to reflect amount of fatty infiltration on histology. In healthy individuals the liver should appear similar in echotexture to the kidneys and spleen, indicating no fatty infiltration; any indication of fatty infiltration supports a diagnosis of NAFLD if there are no other known causes. USS determined fatty liver has been shown in several studies to have high levels of sensitivity (89-90%), specificity (82-93%), positive predictive value (87-93%) and negative predictive value (87-94%), when compared with the gold standard of liver biopsy histology, for diagnosing moderate to profound levels of hepatic fatty infiltration. USS fatty infiltration has high levels of intra- and inter-rater reliability. USS cannot adequately identify liver fibrosis or cirrhosis in general asymptomatic individuals. However, neither can other radiological approaches. Indeed at present fibrosis and cirrhosis can only be diagnosed by biopsy, which as discussed above is not ethical or practical in any research study in health individuals.

Other radiological approaches including standard MRI, MR spectroscopy and CT scan are also able to accurately diagnose NAFLD. These modalities can identify different patterns of hepatic fatty infiltration, such as diffuse or nodular, but the relevance of these is currently unclear and the subject of on-going research. As yet there is no clear evidence that CT, MRI or MR spectroscopy have important benefits when compared to USS in simply identifying fatty liver infiltration.

Thus, USS provides a valid gold standard against which to evaluate ALT, AST, AST:ALT and GGT as biomarkers for NAFLD in adolescents.

Date proposal received: 
Thursday, 22 May, 2008
Date proposal approved: 
Thursday, 22 May, 2008
Keywords: 
Genetics
Primary keyword: 

B658 - Evaluating the utility of liver enzymes as biomarkers for non-alcoholic fatty liver disease in adolescents - 19/05/2008

B number: 
B658
Principal applicant name: 
Prof Debbie A Lawlor (University of Bristol, UK)
Co-applicants: 
Dr Marl Callaway (Not used 0, Not used 0), Prof Chris Day (University of Newcastle, UK), Prof Naveed Sattar (University of Glasgow, UK), Dr Abigail Fraser (University of Bristol, UK)
Title of project: 
Evaluating the utility of liver enzymes as biomarkers for non-alcoholic fatty liver disease in adolescents
Proposal summary: 

Background

Non-alcoholic fatty liver disease (NAFLD) is defined as fatty infiltration of the liver in the absence of alcohol misuse or other causes of liver damage and is probably the most common liver disorder in all ages in the developed world today. NAFLD includes a wide spectrum of liver damage, ranging from simple steatosis to advanced fibrosis and cirrhosis (this advanced form referred to as non-alcoholic steatohepetitis (NASH)). The primary cause of NAFLD is obesity and with the global epidemic of obesity the prevalence of NAFLD and its complications are increasing. NAFLD has recently been described as "a disease of our generation", as clinicians have noted a large increase in liver pathology in all ages driven by the obesity epidemic, in addition to increasing rates of alcohol consumption.

The whole spectrum of NAFLD has been described in children and adolescents. Presentation with, and progression to, cirrhosis in adolescence has also been described. Estimates of the prevalence of NAFLD, based on unexplained elevated levels of alanine aminotransferase (ALT) or USS, range from 2-3% in general paediatric populations, to between 10-30% in obese children or adolescents. These studies suggest that NAFLD is rare before adolescence, findings confirmed in a recent post-mortem study that provides the most robust evidence of the potential importance of NAFLD in adolescents. In that study, of 742 US individuals (aged 2-19 years) who had died from external causes (mostly road traffic accidents) the age, gender and ethnicity standardised prevalence of NAFLD (defined as greater than 5% steatosis on histology of the post-mortem liver) was 9.6%, with 3% of the population having NASH. The prevalence increased with increasing age from 0.7% in those ages 2-4 to 17.3% in those aged 15-19; it was very rare before the age of 10. Of importance, as duration of NAFLD in adults is associated with increased likelihood of progression to severe advanced disease, this means that it is likely that individuals with NAFLD in adolescence are at a very high risk of severe liver pathology in adulthood if fatty infiltration of their liver is not reversed (since by definition having the condition from adolescence into adulthood is a longer duration than fatty infiltration first appearing in adulthood). In one small (N=9) case study of clinically obese children who were referred because of persistently elevated ALT levels, those who complied with a hypocaloric diet were reported as having reductions in ALT levels that paralleled their weight loss. However, stronger epidemiological evidence is required to determine whether evidence of NAFLD in early life is reversible or whether changes in risk factors in early life can reverse evidence of hepatic fatty infiltration, liver damage and its associated adverse metabolic and vascular traits.

We recently found that 6% of a general (healthy) population of white American adolescents (age 12-19 years) had elevated ALT levels indicative of NAFLD (using a threshold of greater than =30 U/L to define NALFD). Furthermore, we showed marked differences in the distribution of ALT by gender (age standardised mean levels lower in girls compared with boys even after adjustment for body mass index (BMI)), which raises the question as to whether the same threshold of defining NAFLD in this age group should be used. We also found mean levels varied by ethnicity and that overtime mean ALT levels in adolescence have increased in this population. We used the publicly available US National Health and Nutrition Examination Survey (NHANES), which is an annually repeated cross-sectional survey that is used for public health surveillance and epidemiological studies in the US. Similar surveys - the Health Survey for England, the Scottish Health Survey and the Welsh Health Survey (http://www.natcen.ac.uk/natcen/pages/or_health.htm) - exist in the UK and are similarly used for public health surveillance and epidemiological studies. We sought to undertake a study of prevalence of elevated ALT and variation in ALT by gender, ethnicity and over time in adolescents in the UK but found that our national surveys did not have information on biomarkers for NAFLD. The lack of such data can be justified because, despite our and others attempts to examine the prevalence of NAFLD in adolescents using liver enzymes as biomarkers, there is currently insufficient evidence evaluating the utility of liver enzymes as biomarkers for NAFLD in adolescents in general or in the UK adolescent population in particular. Liver enzymes are relatively cheap and easy to assay. They would, therefore, be ideal for public health surveillance if they are shown to be accurate as diagnostic biomarkers in adolescents.

The diagnosis of NAFLD is suspected when there are indicative changes in liver enzymes (ALT, aspartate aminotransferase (AST), ALT:AST) and/or echogenic (fatty) liver detected by USS, together with the absence of any established causes of liver disease. A definitive diagnosis, and determination of severity, requires a liver biopsy, which is not feasible in large-scale epidemiological studies. Indeed, since liver biopsies are painful and have rare, but potentially severe, iatrogenic effects even in clinical practice liver biopsy is only recommended when there is a high level of suspicion of liver damage and clear indications that biopsy would alter clinical practice. The British Society of Gastroenterology and the British Association for the Study of the Liver guidelines for the use of liver biopsy in clinical practice state that the role of liver biopsy in the diagnosis and clinical management of NAFLD is currently not established. Similarly the American Gastroenterology Association have noted that the potential health risks, high cost and biopsy sampling errors associated with liver biopsy should be weighted against the value of the information that would be gained from performing a biopsy each patient. In clinical practice a combination of clinical history, measures of adiposity, presence of other associated morbidities, such as diabetes, elevated aminotransferases (ALT, AST and ALT:AST) and imaging modalities (USS, CT scan and MRI) are used and recommended in clinical guidelines for the diagnosis of NAFLD.

In research, elevated aminotransferases (ALT, AST, ALT:AST) have been predominantly used for case definition of NAFLD. However, there is marked variation in the thresholds used to define NAFLD across different studies, even when the same or very similar populations are used. For example, three studies have used ALT to assess NAFLD prevalence in adults from the USA NHANES survey and have used different thresholds - 19, 31 or 43 u/L in women; 40 or 43 u/L in men. Far fewer studies have examined the prevalence of NAFLD in general adolescent populations, but similar variation is found. ALT thresholds of between 30-40 u/L have been use, with identical thresholds used in females and males, despite clear evidence that in adolescence (as in adulthood) the distribution of ALT varies by gender.

There is biological plausibility for all three of ALT, AST and GGT as biomarkers for NAFLD; all are secreted by hepatocytes in response to liver damage, including NAFLD. ALT is the liver enzyme most commonly used in the assessment of liver conditions in general, including NAFLD, though its primary use has been questioned. It is a more specific marker of liver damage than AST, which is also found in the heart, skeletal muscle, kidney and other organs, and than GGT, which is expressed by most cells in humans. ALT elevation is greater than AST elevation in NAFLD and ALT is a more robust predictor of diabetes. Nonetheless elevation in both aminotransferases, ALT and AST, are recommended in clinical guidelines as biomarkers for NAFLD in adults. In NAFLD, plasma levels of both ALT and AST may be increased due to leakage from hepatocytes that have been damaged by fat accumulation. In addition, as ALT has an important role in gluconeogenesis and amino acid metabolism its greater elevation (compared to AST) may reflect increased gluconeogenesis, due to hepatic insulin resistance that is closely associated with liver fat accumulation, in addition to leakage from hepatocytes. Because of the greater ALT compared to AST elevation with NAFLD a low (below 1) AST:ALT ratio has also been suggested as a valid biomarker for NAFLD. The low AST:ALT ratio contrasts to the high (above 1) AST:ALT ratio that is typical of alcoholic liver disease.

GGT levels also increase with NAFLD, although this enzyme is not mentioned in clinical guidelines as part of the screening or diagnostic procedures for NAFLD. This is probably because it is has long been used as a marker of alcohol consumption and because it is expressed in most cell types and is therefore not a liver specific enzyme. In NAFLD, leakage from damaged hepatocytes would explain elevated levels of GGT. Thus elevated GGT levels could equally represent excess alcohol intake or NAFLD. Few adolescents are likely to have experienced the chronic alcohol abuse that is required to cause liver damage. Thus, it is biologically plausible that in adolescents GGT is also a useful biomarker for NAFLD. In this application we will use genetic variants associated with greater fat mass as proxies for fat related increase in GGT, and other enzymes (i.e. NAFLD related enzyme increase). These genetic variants are not associated with alcohol consumption and therefore we are able to use them to examine the extent to which elevated GGT, ALT and AST might be explained by NAFLD as opposed to alcohol consumption or other non-fat causes of liver damage.

Few studies have formally evaluated the utility of ALT, AST, AST:ALT and GGT as biomarkers for NAFLD in adolescents. One study in adults with the more severe form of NAFLD (non-alcoholic steatohepetitis (NASH)) examined the utility of ALT and AST as biomarkers for treatment effects in randomised controlled trials. The motivation of the investigators was their recognition of the need for relatively cheap and non-invasive surrogates even in RCTs of adults with more advanced disease (in whom biopsy would be more likely that in public health / epidemiological studies or trials of preventive interventions in health adolescents). Within a subgroup (N=102) in the trial they compared changes in ALT and AST levels to the main outcomes assessed by liver biopsy. They concluded that both aminotransferases were equally useful in RCTs of treatment for NASH in adults. Utility (assessed by receiver-operating characteristic (ROC) curves) was improved in multivariable analyses that adjusted for baseline ALT and AST levels as well as histological changes obtained from liver biopsy at baseline. In children and adolescents it has been suggested that elevated ALT levels potentially miss up to 40% of individuals with NAFLD.5;31These statements have been made largely on the basis of comparisons of elevated ALT with liver biopsy in clinical obese paediatric populations, who are unlikely to be representative of general populations. Even within clinically obese paediatric populations there are inconsistencies in the findings. For example, one study of obese Japanese children (up to age 16) found that a threshold of 30 u/L of ALT had a sensitivity of 0.92 (i.e. identified 92% of cases) for detecting NAFLD proven by USS. That study tested a particular threshold rather than using ROC curves33 to identify a threshold that maximises both sensitivity and specificity.

Thus, to date, there has been no thorough evaluation of ALT, AST, AST:ALT and GGT as biomarkers for NAFLD in general populations of adolescents. If we find that ALT, AST and GGT either alone or in combination are valid biomarkers for NAFLD they will provide a cheap and easily available marker that could be used widely for public health surveillance, epidemiological research and randomised controlled trials of preventive interventions.

In a healthy liver there should be no or very little fatty infiltration. The formal definition of NAFLD is that just 5% (or more) of hepatocytes have fatty infiltration on biopsy. On USS fat appears as a bright area. The USS indicators of fatty infiltration in the liver are bright hepatic echotexture (compared to the kidneys and/or spleen), deep attenuation and vascular blunting, and the extent of fatty infiltration can be quantified (none, mild, moderate and severe), with this quantification also shown to reflect amount of fatty infiltration on histology. In healthy individuals the liver should appear similar in echotexture to the kidneys and spleen, indicating no fatty infiltration; any indication of fatty infiltration supports a diagnosis of NAFLD if there are no other known causes. USS determined fatty liver has been shown in several studies to have high levels of sensitivity (89-90%), specificity (82-93%), positive predictive value (87-93%) and negative predictive value (87-94%), when compared with the gold standard of liver biopsy histology, for diagnosing moderate to profound levels of hepatic fatty infiltration. USS fatty infiltration has high levels of intra- and inter-rater reliability. USS cannot adequately identify liver fibrosis or cirrhosis in general asymptomatic individuals. However, neither can other radiological approaches. Indeed at present fibrosis and cirrhosis can only be diagnosed by biopsy, which as discussed above is not ethical or practical in any research study in health individuals.

Other radiological approaches including standard MRI, MR spectroscopy and CT scan are also able to accurately diagnose NAFLD. These modalities can identify different patterns of hepatic fatty infiltration, such as diffuse or nodular, but the relevance of these is currently unclear and the subject of on-going research. As yet there is no clear evidence that CT, MRI or MR spectroscopy have important benefits when compared to USS in simply identifying fatty liver infiltration.

Thus, USS provides a valid gold standard against which to evaluate ALT, AST, AST:ALT and GGT as biomarkers for NAFLD in adolescents.

Date proposal received: 
Monday, 19 May, 2008
Date proposal approved: 
Monday, 19 May, 2008
Keywords: 
Primary keyword: 

B653 - Genomewide analysis of autism/autism spectrum disorder related quantitive traits in the ALSPAC cohort - 09/05/2008

B number: 
B653
Principal applicant name: 
Dr Beate Glaser (University of Bristol, UK)
Co-applicants: 
Prof George Davey Smith (University of Bristol, UK), Prof Jean Golding (University of Bristol, UK)
Title of project: 
Genomewide analysis of autism/autism spectrum disorder related quantitive traits in the ALSPAC cohort
Proposal summary: 

Autism is a severe and heritable condition, which belongs together with Pervasive Developmental Disorder NOS, Rett's syndrome, Asperger syndrome and Childhood Disintegrative Disorder to the group of autism spectrum disorders (ASD) (American Psychiatric Association, 1994). ASD usually starts in early childhood and all ASD show strong impairment in reciprocal social interaction. Additionally, syndrome-specific impairment in communication or stereotyped behaviour, interests and activities may be present (American Psychiatric Association, 1994)(WHO, 1992). Associated with ASD are often abnormalities in the development of cognitive skills (mental retardation) and behavioural symptoms like hyperactivity, attention deficits, impulsivity, aggressiveness, self-injury and temper tantrums. (American Psychiatric Association, 1994)(WHO, 1992).

Defined mutations, genetic syndromes and de novo copy number variations account together for approximately 10-20% of ASD cases (Abrahams & Geschwind, 2008). Twin and family studies have however provided additional support for a complex genetic disease aetiology underlying ASD such as shown by the increased similarity of cognitive and behavioural features among relatives (Abrahams & Geschwind, 2008). High heritability estimates for social impairments, communication impairments, and restricted repetitive behaviors and interests have been observed, although the co-variation between these domains was modest (Ronald, Happe, Price, Baron-Cohen, & Plomin, 2006). By contrast, evidence for overlapping genetic influences on comorbid autistic and ADHD behaviours was found in a recent community-based twin sample (Ronald, Simonoff, Kuntsi, Asherson, & Plomin, 2008). These findings suggest an oligogenic disease model for ASD with synergistic action of multiple loci, an assumption that is also supported by distinct linkage signals for ASD endophenotypes (Abrahams & Geschwind, 2008).

Given the importance of common genetic variation in ASD risk, we propose a genome wide association study of autism spectrum disorder related traits in ALSPAC. We furthermore propose that common genetic variation, which is related to autism spectrum disorder quantitative traits, will occur in genes in which more severe mutations will lead to autism.

We will investigate single, multi-marker and epistatic effects using the software Plink, STATA and R. Single marker effects will also be followed up longitudinally. We furthermore aim to identify clusters of endophenotype-related genotypes using hierarchical clustering and PCA. We will investigate homozygocity and segmental sharing across associated genomic regions using Plink and in house developed Perl software.

Date proposal received: 
Friday, 9 May, 2008
Date proposal approved: 
Friday, 9 May, 2008
Keywords: 
Genetics
Primary keyword: 

B648 - Axon Male Adolescence and Mental Health - 06/05/2008

B number: 
B648
Principal applicant name: 
Dr Tomas Paus (Baycrest Centre for Geriatric Care, ROW)
Co-applicants: 
Dr Dave Evans (University of Bristol, UK), Dr Beate St. Pourcain (University of Bristol, UK), Dr Carol Joinson (University of Bristol, UK), Dr Margaret May (University of Bristol, UK)
Title of project: 
Axon, Male Adolescence and Mental Health.
Proposal summary: 

This project builds on our preliminary findings suggesting that, during adolescence, testosterone affects axonal calibre rather than the thickness of myelin sheath and that this effect is moderated by generic variations in the AR receptor. In Aims 1,2 and 4 (see main application), we are taking advantage of the existing longitudinal birth cohort (ALSPAC) that contains a wealth of information about sexual maturation and testosterone levels (at 3 time points), as well as mental health and cognitive abilities, during adolescence. Aim 3 (see main application) will take the first step towards an experimental evaluation of the predicted effects of testosterone on the axon in the rat model.

This is a 5 year programme grant, but ALSPAC costs fall within years 1-4.

Deliverables (ALSPAC)

1. To identify 500 boys with certain variables collected in the past (questionnaire data, or current clinic data) on puberty plus DAWBA, SDQ, DRUGs, PLIKS and bloods for at least 3 time points between ages 9 and 17.

2. To employ a fieldworker(s) to ensure these subjects undergo a structural (and possibly functional) MRI scan at CUBRIC, Cardiff University (under supervision of Prof Derek Jones - subject to a separate arrangement).

3. Saliva samples to be collected for testosterone (added since original proposal - will incur extra costs regarding sample collection, storage, transport and analysis).

4. Administer a computerised questionnaire to the subjects to include CIS-R, PLIKS, substance-use (as in the clinic).

5. Participant recruitment will be reported to the PI so that he may complete the Recruitment Milestone Reporting system in good time. These are due on: April 1st, August 1st, December 1st 2011. The RMR system expects that at least 176 of the 500 subjects will be recruited by 1st April.

6. The statistician will work under the supervision of Beate Glaser and Margaret May on the initial analysis of cohort-based data.

7. The ALSPAC lab technician will support identification, retrieval and preparation of blood and saliva samples for testosterone analyses.

8. The original proposal had participants attending for scans at Bristol Royal Infirmary; however, this has been changed to Cardiff and will increase participant travel considerably.

Date proposal received: 
Tuesday, 6 May, 2008
Date proposal approved: 
Tuesday, 6 May, 2008
Keywords: 
Genetics, Mental Health
Primary keyword: 

B651 - Do filaggrin truncation variants affect hearing - 01/05/2008

B number: 
B651
Principal applicant name: 
Prof Ian Day (Not used 0, Not used 0)
Co-applicants: 
Prof John Henderson (Not used 0, Not used 0), Dr Amanda J Hall (Not used 0, Not used 0)
Title of project: 
Do filaggrin truncation variants affect hearing?
Proposal summary: 

Do filaggrin truncation mutations affect hearing?

This hypothesis is stimulated by a 'case observation' of a proband with residual mild ichthyosis (which was more severe in childhood) and palmoplantar atopic dermatitis. The father is more severely affected. More extended family history is unknown. For ordinary sounds, the proband also has a hearing threshold which is considerably lower than most people, and this was confirmed in an analysis at Dundee University. The father is elderly and his hearing status indeterminate. The most obvious diagnosis would be of one of the common filaggrin truncation mutations causing the dermatological picture, although this has not been proven. Nonetheless, the 'filaggrin/hearing' hypothesis will stand even if this familial picture reflected some other gene. Filaggrin is expressed in skin. It is also expressed in the tympanic membrane (Broekaert 1995). It has also been noted to be expressed in middle ear cholesteatoma (Chao and Huang 1989). Truncating mutations lead to a reduction of filaggrin-keratin crosslinking and altered keratinization and hence to the dermatological picture described above. The high mutation frequency worldwide may simply reflect high mutational drive on account of the structure of the gene, in conjunction with non-lethality of inactivating changes; or there could be a selective advantage to the mutations. Sound transmission involves both the external auditory meatus and tympanic membrane between outer and middle ear, and middle ear. Any structural influence of filaggrin in these locations could lead to filaggrin mutations affecting hearing thresholds and related traits. Hearing and language have formed a crucial part of progression of the human species and relative to the average, better hearing could have conferred both communication and survival advantages. It might even continue to do so in the present day. The purpose of this request is to test whether hearing characteristics are associated with filaggrin gene status. Most subjects with a filaggrin mutation will be heterozygous rather than homozygous. It is suggested therefore to adopt a genetic model in which heterozygotes are tested against wildtype for mean of each relevant hearing trait, and to do descriptives for homozygotes but not to regard them as part of the primary test - this seems reasonable, since, for dermatological features, heterozygosity produces clinical features. The proposed target list of quantitiative traits are those identified by Amanda Hall: hearing threshold at Focus 9 and Focus 11; tympanometry data at Focus 9 and Focus 11 - particularly middle ear compliance and gradient and the acoustic reflex threshold; and lastly, likely as an ordinal analysis, tympanic membrane abnormalities coded from photographs at Focus 9. The analyses will be done using existing resources within the respiratory group, which has recently worked in depth with the FLG data.

Date proposal received: 
Thursday, 1 May, 2008
Date proposal approved: 
Thursday, 1 May, 2008
Keywords: 
Hearing
Primary keyword: 

Pages