Proposal summaries
B658 - Evaluating the utility of liver enzymes as biomarkers for non-alcoholic fatty liver disease in adolescents - 19/05/2008
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.
B653 - Genomewide analysis of autism/autism spectrum disorder related quantitive traits in the ALSPAC cohort - 09/05/2008
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.
B648 - Axon Male Adolescence and Mental Health - 06/05/2008
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.
B651 - Do filaggrin truncation variants affect hearing - 01/05/2008
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.
B645 - The impact of adiposity on risk profiles and the emerging arterial phenotype in the young - 30/04/2008
No outline received
B650 - Genome-wide association studies of ankylosing spondylitis - 28/04/2008
The Australo-Anglo-American Ankylosing Spondylitis Consortium (TASC) has been funded by the NIH and other bodies to perform a genome-wide association study of a large Ankylosing Spondylitis cohort on the Illumina 317K SNP chip. The genotyping for this project has already been completed, and statistical analyses are being finalized. Preliminary analyses have identified several new variants underlying disease risk.
ALSPAC is currently awaiting the imminent arrival of genotype data for 2000 individuals who have been genotyped on the Illumina 317K chip. Inclusion of unselected control individuals can increase power to detect association. I am therefore asking that the committee consider allowing me to pool the ALSPAC genome-wide data with TASC in order to maximize power to detect association in the TASC study. As I will soon be leading the analysis of the genome-wide data in ALSPAC, such a pooling would be trivial to impliment. Additionally, since no phenotype data is required in this proposal, there would be no need for data linkage.
B644 - Prenatal paracetamol exposure asthma and DNA methylation - 21/04/2008
Epigenetic mechanisms are thought to underlie the fetal programming of disease. A number of prenatal risk factors have been implicated in childhood asthma, and the possibility that prenatal epigenetic effects might be important in asthma has been mooted before(1). However, whilst there are indirect clues in support of this hypothesis, such as evidence for maternal line inheritance of asthma suggestive of imprinting, and data indicating transgenerational effects of grand-maternal smoking in pregnancy on asthma risk(2), direct evidence is currently lacking. We have found a positive association between prenatal paracetamol exposure and risk of asthma in ALSPAC and proposed that the underlying mechanism involves glutathione (GSH) depletion(3). This effect has become stronger for asthma at 91 months (odds ratio per category increase in paracetamol exposure 1.33 (95% CI: 1.15 to 1.54), P=0.000092), and the effect was modified by glutathione S-transferase (GST) M1 genotype in the mother and child (odds ratio 3.63 (1.48 to 8.92), P=0.005 if mother homozygous wild (HW) for GSTM1; OR 5.01 (2.13 to 11.74), P=0.00021 if child HW). Given that GSH depletion is thought to impair DNA methylation(4), and epigenetic mechanisms are thought to underlie fetal programming, we speculate that DNA hypomethylation may underlie the effect of prenatal paracetamol on asthma risk observed in ALSPAC.
Hypotheses
1) Prenatal paracetamol exposure leads to DNA hypo-methylation
2) Children with asthma have less DNA methylation than those without asthma
B646 - Early Sign of Autism - 18/04/2008
The purpose of the proposed study is to describe a typical early development of children with childhood autism.
I specialize in the early signs of autism. As a member of Institute for Research on Children, Youth and Family I participate in the ELSPAC study in the Czech Republic.
The number of children with autism in the Czech ELSPAC study is too low and their data lead to inconclusive findings. Thus, we would like to analyse ALSPAC data, if possible. We would like to analyze the ALSPAC parental reports and compare the data from parents of children with autism with the data from parents of children with typical development or with other developmental disorders. We would like to create a typical autistic developmental chart with the symptoms that are the most specific and significant for the future diagnosis of childhood autism. The long term goal is to develop an early screening tool based on these signs.
Early signs of autism are difficult to identify. Even though the parents of children with autism usually start to suspect that there might be a problem in their child's development quite early, the diagnosis of autism is on average not set until three years of age (Filipek et al., 1999). Children with no other associated serious disease or developmental disorder are typically not in contact with a professional other than a pediatrician until they start to attend a kindergarten or school to be compared with their peers. That is why there is a strong need to help pediatricians to identify first signs of this developmental disorder in early infancy (age 0-3) to make possible earlier intervention (such as early speech therapy, motivation to eye-contact etc.).
The ALSPAC study offers an exceptional opportunity to analyze large-sample data about child's development from parental perspective before the time the diagnosis of autism was set and compare them with the same data on the development of typical child. Such data are methodologically and ethically superior to data from retrospective questionnaires because retrospective data are usually less complete and suffer from various memory distortions. Also retrospective questioning of parents of children with autism can have retraumatizing effect.
We assume the early development is culturally independent enough for us to be able to test our hypothesis about the early development of autism on the ALSPAC and ELSPAC samples and compare our findings from these two studies.
Journals like Autism or Journal of Autism and Developmental Disorders will probably be interested in an article on this topic. Institute for Research on Children, Youth and Family supports this research.
B647 - Blood vessels and patterns of brain function in twins - 17/04/2008
Vascular function and cardiovascular risk factors in twins
The twin study was conducted in collaboration with the Multiple birth foundation and, for measures of vascular function, with Professor John Deanfield. We have recruited 210 pairs but require a further 20 pairs (particularly DZ twins). As we have exhausted the available twins from the multiple birth foundation we require additional data from twins collected as part of Professor John Deanfield's collaboration with ALSPAC. These cross-sectional data are already available in Professor's Deanfield's database of the ALSPAC cohort (eg measures of vascular function, demographic and anthropometric data, and conventional cardiovascular risk factors). We require only the identification of twins from this existing database and the method by which the zygosity was determined. We do not require any personal data. This will allow us to include the small number of twins (previously estimated as less than 25 pairs) collected as part of Professor Deanfield's collaboration with ALSPAC to be included in our study and hence achieve our sample size. All vascular measures in both studies have been made using identical techniques.
The twin study was funded by the MRC to test the following 2 hypothesis:
1. In twins discordant for birth weight we tested the hypothesis that low birth-weight is associated with endothelial dysfunction independent of maternal factors and the family environment (including socio-economic status). A twin study in children as opposed to adults allowed us to investigate early stages of atherosclerosis before the onset of lifestyle cardiovascular risk factors common in adulthood. This study has now been completed.
2. That the childhood environment strongly affects development of early atherosclerosis and its risk factors. Justification: Our own and other's data, suggest the atherosclerotic process may begin even in the first decade. But, the relative contributions of genetic and environmental factors to early atherosclerosis (as opposed to clinical CVD) are unknown. A classical twin model in children allow us to define the relative impact of additive genetic factors, and both shared and non-shared environmental factors on early atherosclerosis. The Framingham study (with a less robust family-based rather than twin study design) suggests that inherited genetic factors make a small contribution to early atherosclerosis. Similarly, our preliminary twin data suggest that shared environmental factors (including family environment and nutritional habits) have a major impact on arterial distensibility, while additive genetic factors make little contribution. Outcomes: In same-sex twin pairs aged 6-18years we have determined measures of vascular health such as flow mediated dilation, arterial distensibility and conventional CVD risk factors such as cholesterol concentration, insulin resistance, C-reactive protein concentration and leptin resistance. The relative contribution of additive genetic versus environmental factors to these outcomes will be assessed using published approaches. We require a further DZ twin pairs to complete this study.
B641 - MRC training fellowship for A Fraser Obstetric lifestyle genetic determinants of vascular and metablic traits - 15/04/2008
Aim
To identify the obstetric, lifestyle, and genetic determinants, of variations in vascular and metabolic traits in women in their mid-40s, an age at which few will have died or been on treatment for cardiovascular disease (CVD).
Objectives
1. To determine the association of obstetric factors (BMI and blood pressure at the start of pregnancy, different patterns of changes in weight, blood pressure and glycosuria throughout the antenatal period, gestational diabetes and pregnancy induced hypertension) with variations in vascular and metabolic traits (fat mass, fat distribution, fasting insulin, glucose and lipids, and blood pressure), in women in their mid-40s, and to use this information to determine whether routinely collected antenatal data can usefully predict variations in metabolic and vascular traits in women in their mid-40s.
2. To use genetic variants with established associations with adiposity as instrumental variables to estimate the magnitude of the causal association of variations in average fat mass over the life course with metabolic and vascular traits in women.
3. To determine the different ways in which obstetric, lifestyle (different patterns of cigarette smoking, physical activity, and dietary intake including alcohol consumption) and genetic factors relate to each other to affect variations in vascular and metabolic traits in women in their 40s.
4. Contribute to determining the association of novel genetic variants (that will be identified by bioinformatics and genome wide association studies) with fat mass, fasting insulin, glucose and lipids, blood pressure and smoking, physical activity and alcohol patterns, and replicate these findings in independent studies; and to examine whether there are genetic variants that are related specifically to adverse metabolic profile in pregnancy.
Design & methodology
Study participants are mothers from the Avon Longitudinal Study of Parents And Children. For these women there is an established DNA bank, immortalised cell-lines, and data on obstetric, socio-demographic and lifestyle factors collected repeatedly, since their index pregnancy in the early 1990s. Fat mass, fat distribution and blood pressure measurements (N=5000), and fasting glucose, insulin and lipids (N=2000) will be collected for women attending their offspring's 15 year follow-up clinic (mean age: 44). Relevant statistical methods - generalised linear regression models, multilevel models, instrumental variables analysis - will be used on these data as appropriate.
Medical opportunities
Results from this study will provide the necessary evidence base for developing programmes aimed at preventing CVD in women. Identifying women at risk of future adverse metabolic and vascular risk profiles during their pregnancy is likely to be advantageous as over 85% of women experience a pregnancy and antenatal care, and they may be particularly receptive to preventive interventions at this stage in their life course.
B638 - Anthropometric measures at 17 - 10/04/2008
Link with diet, bone density, weight in early teens
Predictive of life time risk of obesity and CVD etc
Linking to genetics????
Methodology
(Lifted and adapted from core renewal doc):
The measures below have been made at 15+ and at previous clinics, allowing us to examine not only associations between exposures and these measures at 17+ but also to examine the association between exposures and change in these outcomes.
We will measure standing and sitting height to the nearest millimetre with shoes and socks removed using a Holtain stadiometer. Participants will be asked to pass urine (if they have not done so recently) before the impedance is measured. They will then be asked to undress to their underclothes. We will measure weight and leg-to-leg impedance using a Tanita THF300GS body fat analyser and weighing scales. We will measure total and regional fat, lean and bone mass using a Lunar Prodigy dual x-ray emission absorptiometry (DXA) scanner. The Lunar Prodigy uses a narrow-angle fan beam that results in very short acquisition times. Software options enable precise assessments of fat mass, lean mass and bone mass both overall and for the trunk, arms and legs. The scans will be visually inspected and realigned where necessary. We will measure grip strength using the Jamar Hydraulic Adjustable Hand Dynamometer NC70150, which measures isometric strength in kilograms. We will measure resting brachial systolic and diastolic blood pressure oscillometrically using a Dinamap BP pro. Arm circumference will be measured and an appropriate cuff size selected. Two measures of blood pressure and pulse rate will then be made at least one minute apart.
B639 - Replication of genomewide associates for gestational age from the Northern Finnish Birth Cohort 66 in ALSPAC - 09/04/2008
Recently, a genomewide association study was undertaken within the Northern Finnish Birth Cohort ('66). This study was designed around the analysis of ~4-5000 individuals for both early phenotypes and those at a later recorded age (31 yrs). Within the cohort, there are extensive phenotypes available and as such there have been a sereis of analyses undertaken in light of the availability of genomewide data a feature only available in the last few weeks. One area of considerable interest has been with respect to the early phenotypes available for this cohort and as such, analyses on birth weight, birth length, ponderal index and gestational age have been undertaken. Of these, that concerning gestational age has yielded preliminary results of great interest (see appendix) and such that warrant immediate replication before undertaking very large-scale follow-up analyses.
The forthcoming availability of genomewide data for the a selection of the ALSPAC cohort (data which may be interrgated on an in silico basis for the initial stage of this project) majes it possible to seek initial and immediate replication of this signal. We propose initally to take the top signals for gestational age and to recover genotypes for these from the genomewide data (currently being finalised at the Sanger Institute, Cambridge). As suggested by one of the key organisers of this project (Panos Deloukas), this is a plausible exercise and the expediated delivery os select genotypes may allow for the checking of initial findings in this ALSPAC sub set.
Following this, we propose (on the basis of inference made from both the Norther Finnish data and that of the ALSPAC sub set) to take promising signals forward to replication in a sample comprised of (within ALSPAC as one of the sample bases) in both all the children and mothers. We feel that this will allow us then to formulate a roubust argument as to the possible contribution of these data to the literature surrounding the genetic predisposition to pre-term delivery (an field ALSPAC already recognises as important and contributes to directly through alternative collaborations).
This second stage of analysis would be dependent on the initial, rapid, exploration of the Finnish signal and would be derived from funding form the Oxford group.
Overall we wish to (i) seek an initial insight into the top Finnish associated signals in an expediated set of ALSPAC genomewide data (such that can be analyse immediately by Dr N Timpson) and (ii) seek permission to genotye promising signals from this stage (of which there appear naively to be 4-5) withiin the whole ALSPAC cohort.
B635 - Childhood obesity child height and educational outcomes - 02/04/2008
The study is part of the ALSPAC large grant (ESRC), project code B273.
In this study, we aim to examine the effects of childhood obesity and child height on children's educational outcomes. As the relationships between child weight or height and educational attainment are likely to be subject to confounding in observational studies, we wish to test the feasibility of using associated genotypes as instruments in Mendelian randomisation experiments. Within the ALSPAC cohort, data have already been collected on a series of single nucleotide polymorphisms, which are robustly associated with both height and body mass index (BMI), as has been confirmed by large independent studies. As such, we wish to use these (and other available data relating to these intermediate traits of interest) in instrumental variable analyses, allowing us to reappraise the observational relationships between these anthropometric measures and education.
We are conscious of the potential limitations of power within this setting, given that the genetic effects on the intermediate trait are relatively small and the variation in these traits required to shift educational attainment relatively large. However, it will be possible to assess the plausibility of studies such as this with data already collected in the ALSPAC cohort. At this stage, we only seek access to already available data.
As we already have access to the ALSPAC data on child and family background characteristics, we only wish to obtain the genetic markers related to children's obesity and height. We understand we cannot use the individual case identifiers we already have. So if needed, we are happy to provide you with the raw data we are using, so that you can merge in the genotypes and provide us with a new child ID for this study.
B634 - Genetic variants associated with obesity in childhood and early adulthood - 31/03/2008
ABSTRACT
Obesity is major health problem in many developing countries. In the United States, approximately 17% of children and adolescents are overweight and one-third of adults are estimated to be obese (1). Body mass index (BMI) is thought to have a substantial genetic component with heritability estimates of 40 to 70% (2). However, genetic variants related to obesity have proved difficult to find and replicate. With the advent of genome-wide scans, new efforts to comprehensively search the genome have begun to identify common variants associated with susceptibility to obesity, such as the recently discovered common SNP in FTO (3). As part of the Genomic Investigation of Anthropometric Traits (GIANT) consortium, we have pooled the results from genome-wide scans in three cohorts to identify genetic variants associated with BMI in early adulthood (N~5,500). We have identified over 80 promising loci associated with BMI at age 20 with a p-value of 10-5 or smaller and are currently replicating 45 of the top SNPs in an additional 10,000 subjects from other cohorts. We propose to follow-up the loci that are replicated in the ALSPAC cohort to determine if the SNPs are also associated with BMI in childhood.
BACKGROUND
Although inherited factors are thought to contribute to obesity, results from candidate gene and genetic linkage studies of obesity have been largely inconsistent [reviewed in (4,5)]. However, recently, as the result of large genome-wide association studies, common variants in the FTO gene were found to be associated with susceptibility to obesity (3) and obesity-related traits (6). The finding of FTO has spurred renewed interested in discovering additional loci associated with obesity and obesity-related traits and spawned large collaborative efforts, such as the Genomic Investigation of Anthropometric Traits (GIANT) consortium, which is an effort to pool genome-wide scan results from multiple cohorts and identify loci associated with height and obesity.
PRELIMINARY DATA
As part of the GIANT consortium, we have pooled the results from three genome-wide scans (encompassing 2.5 million single nucleotide polymorphisms that were either directly genotyped or imputed) with information on BMI at age 18 or 20 to identify genetic variants associated with BMI in early adulthood (N~5,500). We have identified approximately 87 independent loci with a p-value of 10-5 or smaller for BMI in early adulthood. Some of these loci are located near or in potentially promising genes, and we are currently genotyping 45 of the top loci in an additional 10,000 subjects from other cohorts with information on BMI in early adulthood.
PROPOSED PROJECT
Assuming that some of the loci identified in our initial meta-analysis are replicated in the follow-up cohorts, we propose to genotype those same SNPs in the ALSPAC cohort to determine whether the loci are also associated with BMI in childhood. We estimate that only a few loci will be convincingly replicated in our follow-up cohorts; however, it is conceivable that up to 10 SNPs may warrant further study. We plan to genotype these SNPs in the same children (N~7,500) that were genotyped in the recently submitted manuscript by Loos et al. (7). Similar to the study by Loos et al., we plan to evaluate the association with BMI at ages 7-11 as well as fat and lean body mass as measured by whole-body dual energy X-ray absorptiometry (DEXA) scan at age 9.
DATA REQUESTED
Biological Samples: DNA (~10 ng of DNA per genotype) for children. We plan to genotype up to 10 SNPs depending on the results of our replication study.
Clinical measurements: Height, weight, and BMI at ages 7-11 years for children. Fat, lean body, and bone mass as measured by a whole-body dual energy X-ray absorptiometry (DEXA) scan in children at age 9.
B633 - GSTM1 and cognitive functioning - 31/03/2008
Concept Specific measure Person Source Time point(s)
GSTM1 Del Child DataBase -
GSTM1 Del Mother DataBase -
Cognitive and neurodevelopmental phenotypes in children, measured on the scales of general cognitive, verbal, perceptual-performance, quantitative, memory and motor development, include the MacArtur Communicative Development Inventory (15 mns), the Denver Developmental Screening test (18 mns), the Wechsler Objective Reading Dimension test (WORD, 91 mns), the Wechsler intelligence Scale for Children (WISC, 8.7years), the Wechsler Objective Language Dimension (WOLD test 8.5 years) and the Counting span test (10 years). In addition, child pervasive developmental (DAWBA, Development and Well-Being Assessment, 91 mns) and autism spectrum disorders will be investigated. Genotypic effects of GSTM1 on cognitive and neurodevelopmental outcomes in children will be studied conditional on maternal smoking before, during and after pregnancy, partner smoking, maternal alcohol consumption during pregnancy and type/duration of breastfeeding. Analysis of cognitive functioning in children will be controlled for by birth weight, gestational age at birth, social communications problems (Social Communications Disorder Checklist) and height. Environmental and demographic factors including socio-economic status and maternal factors will be also included in the analyses as covariates.
Multiple regression models, with appropriate adjustment for covariates will be constructed. In addition to categorical coding (2 df test), genotypic effects will be analysed under recessive, dominant and additive disease model assumptions. Recessive coding corresponds to a GSTM1 present vs GSTM1 null analysis. For categorically coded outcomes also deletion-specific analysis will be preformed. For all nominally significant associations empirical p-values will be derived using permutations to account for increased type I error due to multiple testing.
B632 - n-3 fatty acids and cognition in children - 31/03/2008
Several studies published recently have suggested that intake of n-3 fatty acids may influence certain cognitive outcomes in certain populations. This was demonstrated in a group of children with develoment coordination disorder by Richardson & Montgomery (2005). However, whether or not these effects can be found in typically developing children remains an interesting hypothesis.
We propose undertaking a statistical analysis of Food Frequency Questionnaire (FFQ) data gathered from children at 7yrs of age and cognitive measures gathered at around the same age (or slightly older). The aim of this analysis is to investigate potential relationships between reported intake of fish (and therefore n-3 fatty acids) and performance on specific cognitive tasks. The specific cognitive measures we are interested in are listed in the table below.
We will also need data from previous parent questionnaires in order to control for 28 confounding variables identified in a previous study examining mother's intake of fish during pregnancy and childhood neurodevelopmental outcomes (Hibbeln, Davis, Steer, Emmett, Rogers, Williams & Golding, 2007).
We further propose to investigate the relationship between reported dietary intake of n-3 fatty acids and the fatty acid profile of the children's blood samples and whether or not the fatty acid profile of the blood samples correlates with performance on the cognitive measures. This will be subject to availability of the data within the time scale. We understand that the sample analysis is being undertaken in the labs of Dr Joseph Hibbeln at NIH in Washington DC and that the work has commenced and will be available during 2008. Therefore this work will be subject to availablity of the results within the timescale of this project.
B630 - Effect of prenatal smoking exposure on symptoms related to PTSD - 31/03/2008
B637 - The relation between maternal nutrition and hypospadias - a case control study from the United Kingdom - 31/03/2008
The goal of our project is to assess the relationship between maternal nutrition in pregnancy and hypospadias, including associations with key food sources of folic acid and phytoestrogens using data from a 2004 case control study among pregnant women in the UK. Other dietary factors, including the use of different vitamin/mineral supplements, and, as in the earlier ALSPAC study, the role of a vegetarian diet, will also be examined using these data. Since the study was designed for other purposes, the abbreviated food frequency questionnaire which was used consists mainly of food groups instead of specific food items (e.g. questions ask about intakes of fresh green vegetables, dairy products, soy foods). In order to estimate intakes of key nutrients such as dietary folate and selected phytoestogens from the items included in this brief questionnaire, we propose to use external information from the ALSPAC study, which was conducted in a similar population, with more detailed information on intakes of individual food items within these food groups. These data will allow us to identify and rank the food group items on the abbreviated questionnaire as sources of the nutrients of interest, at the population level. We will also use the more detailed external ALSPAC data to examine whether there appear to be meaningful differences in the contribution of food groups to nutrient intakes across different age, ethnic and/or education strata as a result of varying patterns of food item intakes within these food groups. Based on these data, we will determine whether it may be appropriate to develop estimates of nutrient intakes/rankings for particular population subgroups, rather than for the study sample as a whole. Finally, we will use these external ALSPAC data to estimate the proportion of dietary folate and phytoestrogens not covered by the food group items in our abbreviated questionnaire, which was not comprehensive, and to examine the variability in intakes of these omitted items.
Concept: Maternal dietary intakes (food items) during pregnancy
Specific measures: intakes of food items including items from the following food groups:
- Dairy products and eggs
- Soy food
- Beans and peas
- Fruit and vegetables
- Poultry and meat
- Fish and seafood
- Chocolate
- Bread and cereals
- Oil
- Nuts and seeds
Person: Mother
Source: Questionnaire
Time Point: Pregnancy
Other variables:
- Maternal age
- Maternal ethnicity (white, nonwhite)
- Household annual income
- Highest level of maternal education
- Maternal vegetarianism during pregnancy (no, never / yes, in the past / yes, I am now)
- Maternal consumption of organic foods (frequency)
- Maternal Body Mass Index
B636 - Decision Making and gambling behaviour in adolescence a prospective population study - 31/03/2008
Study Aims
The overall aims are to investigate the distributions and correlates of problem gambling in young people, and to describe the developmental trajectories from early childhood of adolescents with problem gambling
Specific objectives:
1. To describe the prevalence of gambling behaviours at 17 years, and their relation to parental gambling patterns.
2. To describe the associations of problem gambling with other risk taking behaviours, alcohol and drug use in adolescence and with debt.
3. To elucidate the interactions between gambling behaviour, developmental conditions such as ADHD and affective states such as depression
4. To investigate the relationship between problem gambling behaviour in adolescents and impulsivity and altered decision-making.
5. To describe developmental trajectories from early childhood of adolescents with problem gambling.
6. In those with a parent who gambles, to investigate the resilience factors which are associated with the young person not developing problem gambling behaviours.
Study design
The Avon Longitudinal Study of Parents and Children is a population-based cohort from the South West of England. Allbirths to women resident in the former Avon Health Authority area, with an expected date of delivery between 1st April 1991 and 31st December 1992 were eligible for enrolment in the ALSPAC study, resulting in a total cohort of 14,062 live births. Active contact is maintained with over 10,000 participants and their parents. At the age of 17 years, the young people and each of their parents will be sent a postal questionnaire (with an option to complete questionnaire online) and the young person will be invited to a research clinic. We will assess the children's and their parents' gambling behaviour and associated cognition in the 17-year questionnaire, and assess the young person's decision-making using a computerised test in the 17-year clinic.
a) gambling behaviour
We propose to use questions from theCanadian Problem Gambling Inventory (CPGI) The CPGI consists of 31 questions: including 'core' items to give a prevalence rate for problem gambling, and other items which are indicators of gambling involvement and correlates of problem gambling to develop a profile of different types of gamblers. Using the CPGI, respondents are classified into five groups: Non-Gamblers, Non-Problem Gamblers, Low Risk Gamblers, Moderate Gamblers and Problem Gamblers. Although ALSPAC previously used the South Oaks Gambling Screen (SOGS) with the parents, the CPGI is preferred because it gives a better spread of categories of gambler.
Problem gambling will be defined using theProblem Gambling Severity Index (PGSI), a 9-item scale derived from the 31 items larger screen. The PGSI is a well validated test which was used in the 2007 BGPS (Wardle, 2007), and in other international prevalence studies (e.g., inAustralia). A validation study (Wenzel, 2004), comparing the performance of the SOGS, the PGSI and the Victorian Gambling Screen (VGS) found that the PGSI outperformed the other two screens. The PGSI items each have four response options. For each item, 'sometimes' is given a score of one, 'most of the time' scores two, and 'almost always' scores three. A score of between zero and 27 is therefore possible, and a threshold of 8 is used to identify problem gamblers., and a score of 3-7 defines 'moderate risk' of PG. Questions from the CPGI, including the PGSI, will be included in the 17-year questionnaires, to be sent to all young people still in the cohort and to both their parents, between January 2009 and June 2010.
b) gambling cognition and decision-making
We propose to use theGambling Related Cognitions Scale(GRCS; Raylu & Oei, 2004) to assess cognition in gambling. The GRCS is a five-factor 23-item questionnaire, which includes questions which cover the wide range of gambling-related cognitive errors that have been reported in the gambling literature. The GRCS asks participants to use a 7-point Likert scale to indicate the extent to which they agreed with the value expressed in each statement. Scoring consisted of totalling the values such that the higher the score the higher the number of GRC displayed. The GRCSwill be included in the 17-year questionnaires, to be sent to all young people and to their parents.
As well as collecting behavioural data to identify types of gamblers (PGSI), and attitudinal data to assess gamblers' cognitive style (GRCS), we believe it is also important to directly test the young people to objectively measure their decision making under gambling conditions. We propose to use a computerised version of The Iowa Gambling Task (IGT), a measure of decision taking under ambiguity. The IGT is based on the Somatic Marker hypothesis (Bechara et al, 1994), and gives information about the development/impairment of orbitofrontal/ventromedial prefrontal cortex. Low performances in IGT have been linked to pathological gambling, alcohol dependence, Parkinson's disease and ADHD (in both adults and children). The IGT can be done manually or computerised: it consists on four decks of cards, two of them bring big wins and big losses, and the other two bring small wins but small losses and in the long-term are advantageous. Participants have different levels of awareness though the test, most participants know and can explain which decks are "advantageous" at card 80 (100 cards possible). Every participant will perform one "round" of the computerized adult version of the IGT (100 cards). Estimated time 10-15 minutes. The computerised IGT will be applied to all ALSPAC participants in the 17-year+ clinic (expected n=6000) between October 2008 and September 2010.
Other measures
The ALSPAC study has extensive epidemiological data regarding parental socioeconomic status, co-morbidity and gambling history measured with the SOGS scale (measured when children were 7 years). The children's behavioural and psychological profile has been measured since infancy, with some measures such as the Strengths and Difficulties Questionnaire (SDQ) repeated at several time points during childhood and adolescence. Psychometric assessments, including measures of cognition, attention and depression in children have been collected at various time points. (see appendix for table of measures already collected).
At 15-16 yrs, the participants have been assessed in the 15+ clinic, with direct measures of IQ (WASI), impulsivity (Stop Signal) and psychopathology (Development and Well Being Assessment- DAWBA). Over 6000 participants were tested in the 15+ clinic.GCSE results on the whole cohort at 16 yrs will be made available by DCSF.
At the 17 year+ clinic, which starts in autumn 2008, young people will complete computerised assessments of mood, funded by a grant from the Wellcome Trust (PI Lewis).We will assess depression and anxiety disorders using the revised clinical interview schedule (CIS-R), that has been widely used in the Psychiatric Morbidity Surveys in the UK, and assess psychological factors, including depressogenic cognitive styles, that are associated with depression and appear to reflect underlying vulnerability. Negotiations are advanced with government departments to fund computerised questions on debt and attitudes to financial risk taking in the 17+ clinic.