Proposal summaries
B714 - Effects of soy infant formula on gender-specific early childhood vocabulary acquisition and time to onset of puberty - 07/10/2008
The aims of the proposed project are to assess the effects of exposure to soy-based infant formula in infancy on 1) vocabulary acquisition in males and females at ages 15 and 24 months, and 2) the time to onset of puberty in males and females. The rationale for this investigation is that soy-based infant formula contains hormonally active phytoestrogen compounds (specifically, genistein and daidzein) which may have the capacity to influence various aspects of neurological and physical development. It is of particular interest to observe how early life exposure to these estrogenic compounds may differentially effect development in boys and girls.
The longitudinal nature of the ALSPAC data makes it an ideal resource for looking at the effects of early life exposures on developmental outcomes occuring later in childhood. This data set contains infant feeding data that would inform us with respect to our exposure of interest [soy, or 'soya,' formula]. Additionally, ALSPAC documentation indicates that vocabulary has been assessed at both 15 and 24 months using the MacArthur-Bates Communicative Development Inventories. Ideally, these vocabulary outcome measures will be combined to develop language acquisition trajectories that can be analyzed via mixed model regression to compare rates across exposures and genders. Multiple measures of pubertal onset (age at menarche, Tanner staging) have also been repeatedly assessed at 5 time points between 97 and 157 months. Survival analysis will be implemented in the analysis of time to onset of puberty.
We do recognize that the prevalence of soy-based infant formula usage is lower in the UK than in the United States, and expect that this will be reflected to some degree in the ALSPAC data. However, given the substantial size of the ALSPAC cohort, we are confident that the proportion of soy exposed infants in ALSPAC will be sufficiently informative and allow for the conduct of sound and meaningful analyses.
An alternative design would be to conduct a randomized control trial of soy-based formula, cow milk formula and breast milk infant feeding regimes. However, this alternative study method is not feasible for the current investigators due to time and other resource limitations. Time is particularly prohibitive for our second outcome of intrest (time to onset of puberty), where approximately 10 or more years would be necessary for all relevent data to be collected. Given that the ALSPAC data has already been collected, using it in the proposed study is certainly the most effecient approach possible.
B713 - The Foetal Programming Hypothesis Examining Prenatal Determinants of Neuroendocrine Activity in the ALSPAC cohort - 07/10/2008
According to the foetal programming hypothesis, factors influencing growth and development in the prenatal and early postnatal periods may affect vulnerability to chronic diseases (e.g., type 2 diabetes, coronary heart disease, etc.). Animal studies suggest that the neuroendocrine system, in particular the hypothalamic pituitary adrenal (HPA) axis, is the primary biological pathway through which this occurs. This has prompted interest in the factors that may affect the foetal HPA axis in humans. Several plausible candidates exist including: prenatal maternal factors that may affect the intra-uterine environment (e.g., depression, smoking etc.) and genes affecting foetal development by regulating the maternal axis (e.g., glucocorticoid receptor and 11beta-hydroxysteroid dehydrogenase (11beta-HSD) isoforms1 and 2 genes). However, the human evidence regarding foetal programming of the HPA axis remains equivocal. This is due, in part, to (i) limitations of existing approaches to assessing the human neuroendocrine system and (ii) a paucity of relevant data on potential environmental determinants of prenatal maternal HPA activity.
This study has sought to overcome these limitations by undertaking a more rigorous assessment of the neuroendocrine system than has previously been possible, through the implementation of the CO2 test. This test provides measures of HPA, sympathetic and parasympathetic reactivity and recovery to a stressor. Furthermore, as our enquiry is based in the ALSPAC (Avon Longitudinal Study of Pregnancy & Childhood) cohort in which environmental data are available on mothers and their offspring, we will be able to examine the relationship between foetal and early life factors (in both mother and offspring) & neuroendocrine activity in offspring at 16 years.
Data we have collected/already have approval to access (ALSPAC proj. B277):
An acute novel stressor (the 'CO2 test') was used in a sub-sample of ALSPAC (N=142). The test involved a single inhalation of 65% oxygen/35% CO2. This acts as a transient physiological challenge activating the key stress-responsive neuroendocrine systems. Consequently, the task produces increases in cortisol, blood pressure and plasma noradrenaline concentrations and an immediate reduction in heart rate that precedes the rise in blood pressure.
In order to explore inter-individual differences in sympathetic and parasympathetic reactivity and recovery, blood pressure and heart rate were recorded every minute from 5 minutes prior to the inhalation and for the 5 minutes post inhalation. Heart rate variability was recorded by the use of a Polar watch over this same time period as the R-R intervals provide assessments of the dynamic vagal regulation of the heart and dynamic changes in baroreceptor sensitivity. HPA activity was captured by the measurement of salivary cortisol (using salivettes) immediately pre-inhalation (-1 minute) and 10, 20, 30 minutes post-inhalation.
In order to control for factors known to affect salivary cortisol: all analyses will allow for time of day when samples were collected and stage in menstrual cycle will be considered for inclusion in the analysis. Participants were also asked to refrain from food and caffeine for at least 1 hour prior to the CO2 task until the final saliva samples have been taken.
In addition 2 psychological measures were administered prior to the CO2 test, the profile of mood states for adolescents (POMS-A) and the 10 item perceived stress scale (PSS-10). This was necessary to allow for inter-individual differences in mood on the day of the stress test.
Existing data on mothers and children will be collated as previously agreed. For mothers, this will focus on prenatal self-reports of social and emotional exposures captured through: (i) indices of quality of social environment; (ii) social support; (iii) distress and (iv) stressful life events. Data on health behaviour exposures (i.e., diet, smoking and alcohol consumption) will also be collated to examine the extent to which the effects of social and emotional exposures on offspring neuroendocrine activity are mediated by health behaviours.
For children, information will be extracted on birth weight, ponderal index and birth weight corrected for gestational age. While the effects of puberty on the neuroendocrine system are not expected to be significant, we will collate growth information from birth and, for girls, data on start of menses so that the effects of pubertal development on neuroendocrine outcomes can be examined.
What biological samples we would like access to and why:
We are seeking to extend the scope of our original application by requesting access to the fasting bloods samples for the 142 volunteers who participated in the stress test at the most recent recall of the cohort (2007/08). We propose to assay plasma cortisol from these samples in order to address the following issues:
1. Explore the relationship betweeen a measure of basal HPA axis function (i.e., plasma cortisol) and measures of HPA reactivity and recovery (i.e., salivary cortisol responses to the CO2 stress test).
2. Examine the relationship between foetal and early life factors and plasma cortisol and whether and how this relationship differs from relationships observed with salivary cortisol.
In addressing these issues, we will also be able to explore the 'added value' conferred by 'stress testing' in this cohort and the most appropriate primary outcomes for future research.
Thus, we are requesting access to 25 ul of the plasma samples collected in heparin containers, from the 142 participants who have participated in our preliminary study. These assays would be conducted in Clinical Biochemistry at the University of Bristol under the supervision of Professor Stafford Lightman.
B709 - Association of brain structure with high risk phenotype for schizophrenia - 03/10/2008
Aims:
We propose to carry out a study examining the neural substrate of an operationally and psychometrically-defined high risk (HR) or intermediate phenotype for the later development of schizophrenia spectrum disorders. This will recruit subjects from the ALSPAC birth cohort and apply structural MRI and voxel-based morphometry. The proposed HR phenotype comprises the combination of persistent (or recurrent) psychosis-like symptoms (PLIKS) between ages 12 and their current age (17), and evidence of stable cognitive deficits at age 8 and age 15. Thus the main aim is: to carry out MRI on a unique epidemiologically based sample of 30 high-risk non-prodromal, non-helpseeking, non-highly familial individuals and 30 matched controls in a nested case-control design within the cohort. Controls will be selected to have either, normal IQ and PLIKS, or, below average IQ but no PLIKS. Such a study will be a once-only opportunity to gather data prior to the peak age of risk. It is essentially a pilot study but will yield important results in its own right and will point the way for work in other modalities (eg spectroscopy and neurochemical imaging). A subsidiary aim is to explore the acceptability of this kind of research to participants in this cohort to offset future attrition.
B708 - Placental surface area and blood pressure in childhood - 03/10/2008
The size of the placenta at birth has been shown to predict blood pressure levels and hypertension in later life. In some studies small placental size predicts raised blood pressure. In other studies raised blood pressure is predicted by high placental weight in relation to birthweight. This latter association is thought to result from compensatory placental expansion in mid gestation. It is well known that if a pregnant ewe is undernourished the fetal lamb is able to extend the surface area of its placenta to extract more nutrients from the mother. This response, however, can only occur if the ewe was well-nourished at the time of conception. Compensatory placental enlargement results in a larger lamb at birth than is seen in pregnancies where the ewe was well-nourished throughout. Inducing placental enlargement in mid-gestation is standard practice in sheep farming.
Almost all published studies in humans are based on placental weight at birth. We have examined the effects of placental surface area in the Helsinki Birth Cohort Study. In the past it was recognised that the surface of the placenta is oval rather than round. In the Helsinki study all placentas were weighed at birth and two diameters of the surface were recorded, a maximal one and a lesser one at right angles to it. Using these diameters it is possible to estimate the area and shape of the placental surface and its thickness. We find that the surface area predicts hypertension more strongly than the weight. Both a small and a large placental area predict the disorder. The association with a large placental area is only found in the offspring of tall mothers, which is consistent with the observations in sheep.
We are requesting permission to photograph the surface of all stored placentae, so that the surface area can be estimated. We recognise that storage will have shrunk the placentae, but one of us is a placentologist and is familiar with the issues. In the proposed study the predictors will be placental weight, the maximal and lesser diameter, measured surface area and measured thickness, body size at birth, length of gestation and mother's body size. The outcome will be systolic and diastolic blood pressure. The analyses will take into account child's age, sex and body size at the time of blood pressure measurement, together with the family's socio-economic status.
We estimate that it will be possible to photograph 300 placentas a week. The Director has told us there are 9,000 placentae and we should therefore be able to complete the photography in 30 weeks.
B710 - Body composition physical activity and diet associations with naevi in ALSPAC - 02/10/2008
(No outline received).
B711 - Genome Wide Association Analysis in Chidlren with Comitant Convergent Strabismus Squint and/or Stereopsis Dysfunction - 01/10/2008
1) Strabismus (Squint)
Strabismus (squint) is a misalignment of the eyes so that they are looking in different directions. It is one of the most prevalent neurological abnormalities seen in children; 2% - 4% being affected in white populations. It is associated with reduced ability to combine the images from each eye and often with reduced vision in one or both eyes. Surgery may be required to alleviate double vision, an abnormal compensatory head posture or most frequently for social and interpersonal difficulties.
There are several types of strabismus. ie different strabismus phenotypes, and there is evidence to suggest heritability for most of these. However, only for some of the rare (approx 5% cases) phenotypes involving incomitant strabismus (ie dependent on the direction of gaze) have specific genetic loci been described (Engle et al). These genes also affect other aspects of brain development. Far more prevalent are the comitant convergent or divergent strabismus phenotypes. These differ in prevalence between ethnic groups, are seen with more concordance in monozygotic than dizygotic twins and are seen more often in individuals with a family history of the same condition (Podgor et al).
There are, however, no candidate genes identified so far which map to more than one family. No Genome Wide Association (GWA) studies for strabismus have been reported to date. Understanding the genetic factors which contribute to keeping the eyes straight will help early identification and treatment of the many affected individuals as well as potentially providing important information about ocular and brain development.
ALSPAC is uniquely well placed to support a small but important study in this area because the study has accurate phenotypic data (at age 7 yrs) enabling the types of strabismus and related defects (eg amblyopia) to be clearly identified and GWA data on a subset of participants. We have already published data on risk factors for the two most frequently seen types of strabismus -convergent (211 children, 2.8%) and divergent (45 children, 0.6%), including an adjusted Odds Ratio (OR) of 2.37 for a positive family history as a predictor of convergent strabismus, after accounting for a key known environmental risk factor (prematurity) (Williams et al 2008).
Thus we will use existing 7-yr vision data ("clinically significant convergent strabismus" as in ref 3, plus amblyopia and or binocular vision data as needed), plus the GWA data
2) Stereopsis (binocular vision)
Stereopsis (depth perception) is one benefit of the fact we have two eyes, separated on the head, from which information can usefully be combined. Other manifestations are motor fusion (the ability to move the eyes separately to keep the object of regard in the visual axis for each eye), diplopia and binocular rivalry. The mechanisms for development of binocular vision remain poorly understood but may well be highly conserved as many species have evolved with two eyes in the front of the head.
Evidence from identical twin studies shows precision of stereoscopic depth perception may be heritable (Wilmer et al). That prevalence of primary monofixation syndrome in parents of children with congenital esotropia (Scott et al) is higher than the general population also supports the hypothesis that a hereditary abnormality in disparity sensitivity may be associated with infantile esotropia (convergent squint).
There are no GWA studies in this area. Some metabolic pathways have been linked to the development of stereopsis or binocular vision eg those relating to plasticity in the visual cortex (Cnops et al) and it can be conjectured that those relating to the metabolism of key neural components such as docosahexaenoic acid (DHA) may be implicated as there is evidence (from ALSPAC) that early exposure to DHA affects stereopsis development (ref 5)
ALSPAC data are ideal for an exploratory GWA analysis of the genetic predictors of stereopsis. We have assessed stereopsis at ages 7 and 11 using a well-established clinical test (the "Randot") and at 12 (n = 2000) using a newly designed stereotest which has been designed to avoid some of the flaws in the Randot and other more established tests. In addition ALSPAC has data on related factors such as strabismus, which may need to be included. Identification of genes involved in this important and basic cognitive function could enhance our understanding of brain development in general and of a range of vision problems, with better identification and treatments made possible. Thus we will use the stereo data and related ocular data as needed, plus the GWA data.
References:
1. Engle. Arch Ophthalmol. 2007;125(2):189-195
2. Podgor et al Arch Ophthalmol. 1996 Jun;114(6):739-44.
3. Williams et al Br J Ophthalmol 2008; 92: 959-964
4. Cnops et al Cerebral Cortex 2008 18(5):1221-1231
5. Williams et al Am J Clin Nutr 2001;73:316-22.
6. Wilmer et al Journal of Vision 2007;7:831
7. Scott et al J Pediatr Ophthalmol Strabismus 1994;31:298-301; discussion 302
B695 - Patterns of parent-child alcohol use in the ALSPAC cohort PhD - 01/10/2008
Aims
We have set three aims, split into sub-objectives:
1 To study underage drinking and heavy drinking episodes in childhood and adolescence:
1.1 To describe the consumption and patterns of alcohol use in youth, investigating possible biases due to drop outs and the accuracy of their reporting;
1.2 To describe changes and trajectories of alcohol use during development;
2 To analyse the social-patterns of alcohol consumption in a parental adult population:
2.1 The frequency, intensity and typology of drinking across different time-points and how they relate with socio-economic position will be addressed;
3 To investigate the role of socio-economic factors and parental exposures on early or heavy episodic alcohol use in young people:
3.1 The relative influence of family income, parental occupation and education and family financial strain on alcohol use in young people;
3.2 The association between parental use of alcohol and alcohol use in the young person.
B706 - Replication of GWAS for dietary energy intake SUPERCEDED BY B712 - 27/09/2008
A genome-wide association (GWA) study that aimed at studying loci associted with childhood obesity was carried out with the Singapore Cohort study of the Risk factors for Myopia (SCORM) samples (n=1004, age 9) using the Illumina 550 SNP chip. After initial genotyping and QC of SNPs and samples, imputation based on HapMap East-Asian samples (Chinese and Japanese) was carried out to increase coverage of SNPs detected in this study. Subsequent association analysis on zscores of BMI revealed several interesting SNPs from genes such as the apolipoprotein B mRNA editing enzyme and the tubby gene, with top p-values in the range of 10-6. Association analysis were also conducted on 695 samples who had relevant measures at birth (birth-weight, birth-length and head circumference), to detect genetic loci associated with obesity at birth.
However, as only a modest sample size (n=1004 at age 9) was available from the SCORM dataset it could be likely that important SNPs fail to reach higher levels of significance and are thus missed from the analyses. As such performing a meta-analysis with the SCORM GWA dataset and the ALSPAC GWA dataset would be useful for both increasing power to detect SNPs that are associated with childhood obesity and possibly reveal more relevant SNPs when they turn up in both these children datasets.
The ALSPAC GWA data carried out with individuals at a similiarly young age (age 11, n=1500+) on the Illumina 330 SNP chip, with relevant obesity measures (height and weight to calculate BMI, birth weight and birth length) and suitable covariates (gender, mother's education status, father's education status) would be used for the meta-analysis with the existing SCORM BMI zscore association results. This ALSPAC dataset would be put through quality control measures to filter of samples based on on call-rate (less than 95%) and gender discrepancies. Subsequently, ethinic confounders would be removed using using principal component analyses. Similarly SNPs would be filtered off based on call-rate (less than 95%), minor allele frequency (less than 0.5%) and Hardy-Weinberg equilibrium (pval less than 1O-7). Subsequently, additional SNPs would be imputed based on HapMap samples to increase coverage of SNPs and overlap between the existing SCORM imputed dataset. Genotype calling for impuation would be based on a posterior probability threshold of 90%. To further ensure confidence of selecting imputed SNPs, those that are solely imputed from both datasets and without any typed SNPs in the region (1.25Mb from the imputed SNP in both datasets) would be filtered off.
SNPs that overlap in both the datasets would be used for detecting association with zscores of BMI and relevant measures at birth for the ALSPAC dataset. This analysis would be done using the linear trend test under various models (additive, recessive, dominant and genotypic) and controlled for relevant covariates such as gender, using the PLINK genome-wide association analysis toolset. Subsequently, individual SNP results (beta, standard error, variance and p-values) from SCORM and ALSPAC datasets would be extracted and used to derive pooled estimates and overall p-values assuming a fixed effect model, with the inverse variance-weighted method. The pooled estimate for the 2 studies would be derived using the formula ? = ∑ w*beta / ∑w (where ? = pooled estimate, w = inverse variance weight of each study and beta= individual beta of each study), which incoporates a weightage for each SNP from the individual study into the overall estimate. Measures of heterogeneity, Cochran's Q and I square statistics would also be generated to gauge the level of heterogeneity between the 2 studies for each SNP. Subsequently, gene annotation of top hits that turn up from this meta-analysis exercise would be carried out to reveal any functional effects the SNP may have on the gene product.
As a follow-up step to the meta-analysis, the remaining subset of ALSPAC samples at age 11 could be used for a replication study and confirm obesity association of possible novel hits that are revealed from the meta-analysis. A tagging SNP approach would be used to best cover the top hits (pval less than 10-4 from the meta-analysis) and the suitable set of SNPs could be genotyped in the Illumina Golden-gate mutiplex genotyping platform.
Concept Specific measures Source Time points
Obesity Anthropometry measures Children in Focus Birth to 12 months
Obesity -Anthropometry measures Focus Clinic Sessions Age 7 to 11
- Measures
-Food and activity
-Health utilities index
-nutrition
B704 - The relationship between beta catenin gene variants and bone development - 26/09/2008
Genome-wide association analyses have recently been conducted in around 1500 ALSPAC children, and related to measures of skeletal phenotype as assessed by total body DXA scans obtained in the focus@9 clinic. One of the strongest associations was between polymorphisms in the osterix gene (a 'master gene' involved in regulating osteoblast differentiation) and bone mineral content, which were subsequently replicated in a further 3500 ALSPAC children. Another assoication observed in this genome-wide analysis was between two genetic variants in CTNNB1 and area-adjusted BMC, suggestive of an influence on cortical thickness. CTNNB1 encodes beta-catenin, which is also involved in regulating osteoblast differentiation, and has recently been found to interact with osterix (1). Also, based on analysis of the phenotype of mice with targeted gene deletion of beta catenin in osteocytes, beta catenin may play an important role in regulating cortical thickness (2).
As a next step, we now wish to genotype the remainder of the ALSPAC children for the two CTNNB1 genotypes in question, namely rs1798802 and rs4135385, with the aim of replicating the associations described above. This will be performed by Kbiosciences using existing DNA samples. As part of this project, we are also keen to examine associations between these genotypes and more direct measures of cortical thickness obtained from pQCT scans (results from these scans performed in the whole ALSPAC cohort at age 16 years will be available shortly). We are also keen to establish whether similar associations are evident in other chorts with GWAS and pQCT data (e.g. the GOOD cohort in Sweden comprising 1000 18 year old men, the Twins study).
1. Zhang C, Cho K, Huang Y, Lyons JP, Zhou X, Sinha K, McCrea PD, de Crombrugghe B 2008 Inhibition of Wnt signaling by the osteoblast-specific transcription factor Osterix. Proc Natl Acad Sci U S A 105(19):6936-41.
2. Kramer I, Halleux C, Brander-Weber P, Feng JQ, Boisclair J, Keller H, Kneissel M 2008 Osteocyte-specific ablation of canonical wnt signaling induces severe osteoporosis. J Bone Miner Res 23, Supplement 1:S12.
B707 - Biological Mechanisms Underlying the Altered Breast Cancer Risk Following Pregnancy - 24/09/2008
AIMS
Primary
1. To test the hypothesis that maternal concentrations of anti-angiogenic factors (i.e. sFlt-1, s-ENG) are reduced and pro-angiogenic factors (i.e. PlGF) are elevated in women who subsequently developed breast cancer compared with women who did not develop breast cancer.
Secondary
2. To test the hypothesis that maternal concentrations of reproductive hormones including estradiol, androstenedione, testosterone, prolactin and hCG differ between women who subsequently developed breast cancer compared with women who did not develop breast cancer. (progesterone, afp and IGF axis also interesting but have been looked at previously.)
3. if blood pressure is available To test the hypothesis that maternal concentrations of anti-angiogenic (i.e. sFlt-1, s-ENG) and pro-angiogenic (i.e. PlGF) factors mediate the association of high MAP, systolic blood pressure increases between the second and third trimesters and breast cancer risk. Also, if possible placental infarcts.
4. if data are available To test the hypothesis that MAP, blood pressure changes and placental characteristics are associated with risk of all cancers, and particularly site-specific tumors.
B705 - Replication of the top-ranked SNPs from the SCORM GWAS for myopia in the sample cohort of ALSPAC and combined meta-analysis of GWAS data for myopia from the ALSPAC and SCORM studies - 23/09/2008
(No outline received).
B703 - The role of haptoglobin and amylase copy number in child and adolescent health - 16/09/2008
A novel method for high throughput genotyping of copy number variation (CNV) has been developed by Dr Philip Guthrie within Bristol Genetic Epidemiology Laboratories. This has been optimised for two CNVs: haptoglobin and salivary amylase. This project aims to genotype these two polymorphisms in the ALSPAC cohort.
Haptoglobin (HP) copy number
Haptoglobin acts as an antioxidant by limiting peroxidative tissue damage by free hemoglobin, which it specifically binds with high affinity. It has also been reported to associate with vitamin C level. Haptoglobin allele Hp2 comprises a 1.7kb duplication encompassing exons 3 and 4, relative to allele Hp1. Hp2 carriers form protein multimers which have reduced availability to tissues, and have been claimed to be associated with higher rates of diabetic vascular complications. Most genetic studies have been conducted by serum phenotyping since there remains a shortfall of DNA-based assays of the duplicon structure.
The only known qualitative difference of allele Hp2 from Hp1 is the presence of the junction sequence between the duplicated segments. We have developed a liquid-phase assay for this junction which is simple, robust, economical and high throughput, and we have applied it to analyse the BWHHS (female) and CAPS (male) cohorts. These studies revealed apparently gender-specific associations. For example, BWHHS showed associations between Hp genotype and haemoglobin level, erythrocyte count and coronary heart disease, whereas Caerphilly showed only a non-significant trend for haemoglobin level in the same direction as in BWHHS.
Analysis of the ALSPAC cohort for Hp genotype will greatly increase the power of this study and help to elucidate further the roles of sex difference in modulating the effects of genotype.
This assay would typically require 10ng genomic DNA. DNA from cell lines is unsuitable, as it may have additional variation in copy number not present in the original sample. We would, however, like to carry out a pilot study using e.g. 100-200 samples replicated between genomic and cell line DNA, to verify/quantify this phenomenon.
Salivary Amylase (AMY1) copy number
Amylase is the enzyme responsible for starch hydrolysis, and the salivary amylase gene AMY1 shows extensive variation in diploid copy number, varying from 2 to 16 copies. A recent study concluded that the pattern of variation in copy number of this gene is consistent with diet-related selection pressures. We have generated an additional hypothesis, which is that copy number of this gene is likely to be more strongly associated with selection pressures generated from interaction between the amount of gene product and some species of Streptococci, which capture amylase onto their coats for their own ends; this in turn influences which other pathogens can colonise or infect the mouth/pharynx, with possible disease-related outcomes due to competition between Streptococci and other buccal micro-organisms
We have developed a liquid-phase assay to determine copy number of this gene, which is simple, robust, economical and high throughput. This assay would typically require 10ng genomic DNA. DNA from cell lines is unsuitable, as it may have additional variation in copy number not present in the original sample. We would like to carry out a pilot study using e.g. 100-200 samples replicated between genomic and cell line DNA, to verify/quantify this phenomenon.
B701 - Unlocking the evidence of infant and maternal health and diet from tooth enamel - 12/09/2008
Tooth enamel represents a durable archive of developmental events in early life. Incremental growth markers laid down during the secretory (matrix formation) stage of enamel formation provide an exact record of the age of onset of mineralization of different areas of enamel. This can be used as an accurate chronological framework that can be related to developmental events such as birth and weaning.
The neonatal line is present in all deciduous teeth in humans and is an accentuated growth increment in enamel and dentine (Schour 1936, Skinner and Dupras 1993). It can be used to identify the portion of enamel that initiated formation before and after birth, and the expression of the neonatal line has been considered an indicator of the severity of neonatal stress during labor and birth. However, this assumption has not been properly tested and the underlying mechanism remains uncertain.
Accentuated striae of Retzius are growth disruptions which reflect a temporary disruption of enamel matrix secretion and have been regarded as a non-specific indicator of systemic stress (FitzGerald et al. 2005). The relationship between the number and distribution of enamel growth disruptions and factors such as socioeconomic status, infant diet, maternal smoking, maternal anxiety, and growth faltering has not yet been tested.
The chemical composition of deciduous tooth enamel is dependant on environmental exposure and physiological influences during the prenatal and postnatal stages of enamel formation. The distribution of trace elements such as strontium, lead and zinc within enamel reflect differences in the age of exposure and in the incorporation of each element into enamel. These patterns can be used to interpret dietary intake and other environmental influences (Humphrey at al 2008 a, b). Analysis of a well documented sample will be used to test assumptions and refine interpretations.
The objectives of the proposed project are to:
1) Evaluate the expression of the neonatal line in relation to mode of delivery (caesarian, spontaneous or instrument assisted delivery), parity status of the mother, maternal anxiety and APGAR score (where available).
2) Evaluate the position of the neonatal line within the enamel crown in relation to birth weight and gestation length.
3) Develop a longitudinal record of enamel growth disruptions in enamel secreted before and after birth for each individual using accentuated striae of Retzius, and relate these records to socioeconomic status, infant diet, maternal smoking, maternal anxiety, and growth faltering measured in the first year of life.
4) Develop spatial maps of the distribution of calcium normalized trace element intensities across each tooth crown, and relate these intensities to mode of feeding at birth, age of introduction of complementary foods, dietary intake, and other environmental exposures (e.g. maternal smoking) and outcomes.
Methods
This project will use naturally shed deciduous teeth donated by approximately 95 children from the core ALSPAC sample. One deciduous canine will be sampled from each child, and we will also select 20 incisors from the study population that have the least amount of wear. High resolution dental casts and micro-CT scans will be produced for each crown prior to sectioning to preserve information on internal and external morphology and ground sections of each tooth used will be returned at the end of the study to extend the usefulness of the collection.
A longitudinal thin section of enamel approximately 100 micrometers thick will be prepared and used for both chemical analysis and a detailed histological study. The neonatal line will be used to identify the portion of enamel that initiated formation before and after birth and also as a baseline for establishing a chronological framework within the enamel crown. Accentuated striae of Retzius (growth disruptions) will be identified following the criteria of FitzGerald et al (2006). Individual chronological records of growth disruptions experienced during the period of tooth crown formation will be established by relating the position of defects to normal incremental growth markers in enamel (Dean et al 1993, Dean 2000, Reid and Dean 2000).
The LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) facility in the Department of Mineralogy at the Natural History Museum will be used to determine calcium normalised trace element intensities at approximately 60 sampling locations in each enamel cusp. LA-ICP-MS combines discrete microanalysis with exceptional spatial resolution and very low detection limits, and is minimally destructive. Data on the distribution of a range of trace elements, including strontium, barium, iron, magnesium, manganese, lead, selenium, and, if possible, cadmium will be collected simultaneously. Geographical Information Systems (GIS) will be used to visually and statistically compare normalised elemental intensities.
We will assess several measures of infant health and diet in relation to deciduous tooth enamel histology and chemical composition (Table 1). Detailed data on a range of attributes and behaviours potentially relevant to health have already been collected in this well-documented sample of children. These include measures of socioeconomic position at birth and in late childhood, parental smoking during pregnancy, birth weight, gestation length and APGAR score and infant diet. This project will address a number of specific and testable hypotheses concerning how these attributes are reflected in enamel structure and composition. The project will also provide baseline data on each of these enamel parameters in a contemporary population. It is also expected that this detailed study will inform appropriate sampling strategies for future epidemiological research using the ALSPAC cohort or other tooth collections.
References
Dean, M.C., Beynon, A.D., Reid, D.J. and Whittaker, D.K. (1993) Longitudinal study of tooth growth in a single individual based on long and short period incremental markings in dentine and enamel. International Journal of Osteoarchaeology. 3: 249-264
Dean, M.C. (2000) Incremental markings in enamel and dentine; what they can tell us about the way teeth grow. In: M.Teaford, M. Meredith Smith and M. Ferguson (eds) Development, Function and Evolution of Teeth. Cambridge University Press. pp. 119-130.
FitzGerald, C. and Saunders, S. (2005) Test of histological methods of determining chronology of accentuated striae in deciduous teeth American Journal of Physical Anthropology 127: 277-290.
FitzGerald, C., Saunders, S., Bondioli, L. and Macchiarelli, R. (2006) Health of infants in an Imperial Roman skeletal sample: Perspective from dental microstructure. American Journal of Physical Anthropology 130: 179-189.
Humphrey, L.T., Dean M.C., Jeffries T.E. and Penn, M. (2008) Unlocking evidence of early diet from tooth enamel. Proceedings of the National Academy of Sciences 105: 6834-6839.
Humphrey, L.T., Jeffries T.E. and Dean M.C. (2008) Micro spatial distributions of lead and zinc in human deciduous tooth enamel. In: J.D. Irish and G.C. Nelson (eds) Technique and Application in Dental Anthropology. Cambridge University Press, pp 87-110.
Reid, D.J. and Dean M.C. (2000) Brief communication; The timing of linear hypoplasias in modern human anterior teeth. American Journal of Physical Anthropology. 113; 135-139.
Schour, I., 1936. Neonatal line in enamel and dentin of human deciduous teeth and first permanent molar. Journal of the American Dental Association. 23: 1946-1955.
Skinner, M. and Dupras, T. (1993) Variation in birth timing and location of the neonatal line in human enamel. Journal of Forensic Sciences, 38: 1383-1390.
B700 - Association of early rapid growth with neurodevelopment in childhood - 10/09/2008
Catch-up growth in early infancy is associated with overweight in childhood (1), but seems to lead to benefits in neurodevelopment in SGA infants (2, 3). This rises the question whether catch-up growth should be avoided or not (4). To our knowledge, there are no studies on the effect of early rapid growth on neurodevelopment in AGA and LGA infants.
We performed a pre-analysis on a merged dataset from four independent clinical trials originally designed to test the effect of LCPUFA supplementation in term and preterm infants (5-8). The data were provided in the framework of EARNEST (9) and included a total of 871 children (495 term, 376 preterm). Neurodevelopment had been assessed by Bayley Scales of Infant Development II (BSID II) at 18 months (10).
Our results indicate a possible benefit of rapid growth in respect to neurodevelopment in both term and preterm infants. However, the analysis is limited by its relatively small sample size and by the assessment of neurodevelopment by Bayley Scales at 18 months which may be an outcome variable of minor relevance.
Within ALSPAC, the required data to answer this research question are available. We would require the following variables from the data set:
o Weight, height and head circumference at birth, 4, 8 and 12 months
o Assessment of cognitive function (at the latest available age)
o Sex
o Gestational age
o Maternal age
o Maternal and paternal education / profession
o Smoking in pregnancy
o Breastfeeding
References:
1. Ong KK, Ahmed ML, Emmett PM, Preece MA, Dunger DB. Association between postnatal catch-up growth and obesity in childhood: prospective cohort study. BMJ 2000;320:967-71.
2. Lundgren EM, Cnattingius S, Jonsson B, Tuvemo T. Intellectual and psychological performance in males born small for gestational age with and without catch-up growth.Pediatr Res 2001;50:91-6.
3. Latal-Hajnal B, von Siebenthal K, Kovari H, Bucher HU, Largo RH.Postnatal growth in VLBW infants: significant association with neurodevelopmental outcome. J Pediatr 2003;143:163-70.
4. Postnatal growth, neurodevelopment and altered adiposity after preterm birth--from a clinical nutrition perspective. Acta Paediatr 2006;95:909-17.
5. Bouwstra H, Dijck-Brouwer DAJ, Boehm G, Boersma ER, Muskiet FAJ, Hadders-Algra M. Long-chain polyunsaturated fatty acids and neurological development outcome at 18 months in healthy term infants. Acta Paediatr 2004;94:26-32.
6. Lucas A, Stafford M, Morley R, et al. Efficacy and safety of long-chain polyunsaturated fatty acid supplementation of infant-formula milk: a randomised trial. Lancet 1999;354:1948-54.
7. Fewtrell MS, Morley R, Abbott RA, et al. Double-blind, randomized trial of long-chain polyunsaturated fatty acid supplementation in formula fed to preterm infants. Pediatrics 2002;110:73-82.
8. Fewtrell MS, Abott RA, Kennedy K, et al. Randomized, double-blind trial of long-chain polyunsaturated fatty acid supplementation with fish oil and borage oil in preterm infants. J Pediatr 2004;144:471-9.
9. Fewtrell MS; EARNEST consortium. Session 6: Infant nutrition: future research developments in Europe. EARNEST, the early nutrition programming project: EARly Nutrition programming - long-term Efficacy and Safety Trials and integrated epidemiological, genetic, animal, consumer and economic research. Proc Nutr Soc 2007;66:435-41.
10. Bayley N. Bayley Scales of Infant Development, 2nd edn.San Antonio, TX: Psychological Corporation; 1993.
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A growing body of epidemiological and experimental evidence indicates that the prenatal period is a sensitive period for later health outcomes, and prenatal priming is a term increasingly used to describe the long term effects on health outcomes programmed by prenatal and early postnatal factors (1). While the roles of maternal obesity (2), maternal smoking in pregnancy (3), gestational diabetes and birth weight (4) are established, there are only few publications assessing the association between gestational weight gain (GWG) and childhood obesity (5-8).
The potential impact of GWG is of particular interest since increases in GWG have been reported in several populations (9, 10), and because GWG may be modified by diet or exercise (11, 12).
A cooperative analysis of the ALSPAC data of Andy Ness and Richard Martin and collaborators from our institution to assess these interdependencies is proposed. We would require the following variables from the data set:
Child:
* Weight and height at latest available age
* DXA at age of 11 years
* Birth weight
* Sex and age
* Gestational age at birth
* TV consumption
* Physical activity (self-reported and objective, if possible)
* Energy intake (calories, protein, fat, carbohydrates, saturated / unsaturated fat)
Mother:
* Weight gain in pregnancy
* Age at delivery
* BMI before pregnancy
* Education / profession
* Smoking in pregnancy
* Breastfeeding
* Married / unmarried
* Gestational diabetes
* Diabetes mellitus
* Pre-eclampsia
* Maternal birth weight
* Parity
References:
1. Gillman MW. Developmental origins of health and disease. N Engl J Med. Oct 27 2005;353(17):1848-1850.
2. Whitaker RC. Predicting preschooler obesity at birth: the role of maternal obesity in early pregnancy.Pediatrics. Jul 2004;114(1):e29-36.
3. Von Kries R, Bolte G, Baghi L, Tochke AM.Parental smoking and childhood obesity - is maternal smoking in pregnancy the critical exposure? Int J Epidemiol. 2007;doi:10.1093/IJE/dym239.
4. Oken E, Gillman MW. Fetal origins of obesity. Obes Res. Apr 2003;11(4):496-506.
5. Moreira P, Padez C, Mourao-Carvalhal I, Rosado V. Maternal weight gain during pregnancy and overweight in Portuguese children. Int J Obes (Lond). Apr 2007;31(4):608-614.
6. Oken E, Taveras EM, Kleinman KP, Rich-Edwards JW, Gillman MW. Gestational weight gain and child adiposity at age 3 years. Am J Obstet Gynecol. Apr 2007;196(4):322 e321-328.
7. Schack-Nielsen L, Mortensen EL, Michaelsen KF, TIA S. High maternal pregnancy weight gain is associated with an increased risk of obesity in childhood and adulthood independent of maternal BMI [abstract]. Pediatr Res. 2005;58:1020.
8. Seidman DS, Laor A, Shmer J, Galr R, DK S. Excessive maternal weight gain during pregnancy and being overweight at 17 years of age. [abstract]. Pediatr Res. 1996;39:112A.
9. Schieve LA, Cogswell ME, Scanlon KS. Trends in pregnancy weight gain within and outside ranges recommended by the Institute of Medicine in a WIC population.Matern Child Health J. Jun 1998;2(2):111-116.
10. Bergmann RL, Richter R, Bergmann KE, Plagemann A, Brauer M, Dudenhausen JW.Secular trends in neonatal macrosomia in Berlin: influences of potential determinants. Paediatr Perinat Epidemiol. Jul 2003;17(3):244-249.
11. Artal R, Catanzaro RB, Gavard JA, Mostello DJ, Friganza JC. A lifestyle intervention of weight-gain restriction: diet and exercise in obese women with gestational diabetes mellitus. Appl Physiol Nutr Metab. Jun 2007;32(3):596-601.
12. Wolff S, Legarth J, Vangsgaard K, Toubro S, Astrup A. A randomized trial of the effects of dietary counseling on gestational weight gain and glucose metabolism in obese pregnant women. Int J Obes (Lond). Mar 2008;32(3):495-501.
B696 - Iron-related gene polymorphisms and birth weight - 09/09/2008
In a study in the North of England, we first confirmed the birth weight association in childhood ALL and hypothesized that iron-related gene polymorphisms may explain this association by increasing both birth weight and childhood ALL risk. We tested this hypothesis, on 995 infants and their mothers from The North Cumbria Community Genetics Project (NCCGP) and 168 cases with childhood ALL from the Newcastle Haematology Biobank in a comprehensive study of the hereditary hemochromatosis gene HFE and other selected iron-related genes including the transferrin receptor gene TFRC (Dorak et al, MS submitted). We found that certain materno-fetal genotype combinations involving HFE and TFRC that increase fetal iron exposure resulted in higher birth weight in boys only and elevated ALL risk mainly in girls. Maternal effect was evident in mother-child pairs when mothers were positive for HFE variants, presumably increasing the amount of iron available for materno-fetal transfer. Our interpretation was that iron-related gene polymorphisms affected placental iron transport and males were able to use excessive iron by increasing fetal growth but girls were not. Greater cell proliferation rate in male fetuses would cause this dichotomy. Ultimately, boys would suffer less from the genotoxic effects of (free) iron but girls would have high amounts of iron increasing their risk for leukemia. Limited data on cord blood iron levels suggested that that when (1) the mother was positive for any of the three HFE variants that increased birth weight, (2) the offspring was male and (3) the male infant was positive for HFE and TFRC variants, birth weight would reach extreme values and cord blood iron would still be high. Thus, only the materno-fetal genotype combinations that increase iron levels most extremely would increase both birth weight and ALL risk in boys. This study suffered from lack of statistical power, especially for the assessment of interactions, and lack of plasma samples in sufficient quantity from mother-child pairs. There was only limited opportunity to increase the sample size due to availability of DNA samples from further mother-child pairs.
We are applying to ALSPAC to replicate this study with greater statistical power in a larger cohort of mother-child pairs and to take advantage of (1) pre-existing data on iron levels at birth, especially in cord slices, and at intervals after birth, (2) pre-existing genetic data on other genetic polymorphisms influencing birth weight, (3) the availability of data on post-natal diet and growth as well as any health outcome. The ALSPAC cohort would also provide the study with data on gestational iron supplementation, birth order, sex of previous birth(s), maternal prepregnancy weight and maternal smoking, that have been reported to influence birth weight or may be relevant for the sex-specificity of the combined HFE and TFRC association with birth weight. For our purposes, the Children in Focus (CiF) subset of ALSPAC will be most useful. We propose to carry out initial studies on CiF samples and extend positive findings to the complete ALSPAC cohorts. Thus, initial genotyping studies will take place at HUMIGEN, Genomic Immunoepidemiology Laboratory (year 1) and any association found or suggested will be replicated in the whole cohort at K-Biosciences (year 2).
The Newcastle study and our ongoing studies in the Genomic Immunoepidemiology Laboratory in HUMIGEN have identified the low penetrance HFE mutations involved in iron overload, C282Y and H63D, to be relevant in birth weight and leukemia associations but have also identified an HFE intron 1 SNP (rs9366637) as a strong predictor of birth weight. In addition, a detailed analysis of the HFE region suggested new susceptibility markers for childhood leukemia. The SNP rs10425 outside HFE appears to be a marker for the wildtype HFE haplotype along with rs807212 and rs12346. In addition to the HFE SNPs, we plan to include the TFRC SNP rs3817672 (S142G), transferrin (TF) SNPs rs1049296 and rs4481157, hepcidin (HAMP) SNP rs7251432, hephaestin (HEPH) SNPs rs5919015, rs809363, rs4827365, ceruloplasmin (CP) SNPs rs710573, rs7652826, bone morphogenetic protein 2 (BMP2) rs235756, hemojuvelin (HFE2 / HJV) SNP rs4970862, ferroportin (HFE4 / SLC40A1) SNP rs2304704, solute carrier family 11 (proton-coupled divalent metal ion transporters), member 2 (SLC11A2 / NRAMP2) SNP rs422982 and transmembrane protease, serine 6 (TMPRSS6) SNP rs733655. We will include these SNPs as a minimal set of iron-related gene polymorphisms and add any other SNPs that our ongoing studies may identify in these genes and other iron pathway genes as new candidates. We will include two HLA-G polymorphisms (rs16375 and rs1233334) also in the extended HLA class I region (between HFE and the HLA complex) because of their potential influence on fetal growth rates. HLA-G has been implicated as the human equivalent of the mouse Ped gene which regulates fetal growth rate. We will examine the HLA-G polymorphisms for their role in birth weight determination and to exclude as a confounder of the HFE association. To achieve these genotypings, we will need 200-250 nanograms of genomic DNA from each mother-child pair in the CiF group. Depending on the amount of already available data in cord blood iron parameters, we may need cord blood serum for iron and ferritin measurements.
If we get the expected results, genotypes or their combinations increasing materno-fetal iron transfer will correlate with birth weight increase in boys but not in girls except the HFE intron 1 SNP rs9366637, which appeared to associate with birth weight in boys and girls in the NCCGP cohort. We will seek correlations between genetic markers and maternal and cord (tissue/blood) iron levels to elaborate our preliminary observations on the NCCGP samples. We expect to find a weak inverse correlation between birth weight and cord iron parameters in boys because of iron depletion by increased growth rate. Seemingly paradoxically, however, we expect to find increased cord iron levels in boys in the presence of certain materno-fetal combinations of iron-related gene polymorphisms. It is this subset that we propose as the basis of birth weight association in leukemia. It will be of great interest to analyze pre-existing data on blood iron level changes during early childhood in these boys to find out whether any genotype maintains high blood iron levels throughout childhood. In a future study, these data can also be correlated with (iron-induced) oxidative stress and genotoxicity assay results.
Iron measurement in cord blood or tissue is an end-point analysis. Our preliminary data suggest that cord iron levels are a cumulative result of materno-fetal iron transfer, fetal cell proliferation rate and duration of gestation. The overall dynamic process of fetal iron levels cannot be reliably quantitated by a single end-of-pregnancy measurement. According to our model, the fetus may be exposed to high levels of (free) iron that causes the genotoxic damage but the cord blood iron level may be low due to accelerated growth towards the end of pregnancy. Since real-time monitoring of fetal iron levels is not possible in humans, ultimately animal experiments will be required to examine this hypothesis. At this stage, we are not planning to propose any animal studies till we obtain more robust data supporting our preliminary findings.
B692 - THE DEVELOPMENT OF MATHS CAPABILITIES AND CONFIDENCE IN PRIMARY SCHOOL - 28/08/2008
Four specific research questions will be addressed to attain the aims specified in the section justification of the method.
1. Are there differences in the development of specific types of mathematical understanding and, if so, how do these influence pupils' progression across the Key Stage 1-3 period?
Learning to think quantitatively and learning arithmetic are two different studies. One previous study with relatively few children has shown that their mathematical reasoning in Year 1 predicts KS1-Maths performance independently of the children's knowledge of numbers at school entry (Nunes et al., 2007) and that improving children's reasoning in Year 1 significantly enhances their KS1 results one year later. An analysis of the ALSPAC data could provide a demonstration of a predictive relation between mathematical reasoning measured in Years 4 and 6 and KS2 and KS3 achievement, independently of knowledge of arithmetic. This could provide much needed evidence regarding later mathematics learning.
The ALSPAC dataset contains four types of predictors to be used in this investigation: (1) cognitive and (2) affective factors; (3) predictors related to teachers' and schools' practices; (4) a set related to the family and the socio-economic background.
The predictors relevant to this first research question are the cognitive measures, which include assessments of the children's:
a) mathematical reasoning (Years 4, 6 and 8 assessments);
b) knowledge of arithmetic (a sub-test of the WISC);
c) working memory (backward digit span), short-term memory (non-word repetition and forward digit span) and attention (a specific measure of attention and a scale within the Strengths and Difficulties Questionnaire);
d) general intelligence (Weschler Intelligence Scale for Children: WISC).
Regression analyses will be used to investigate whether each of the first three of these measures makes a distinct contribution to predicting students' mathematics achievement at each KS assessment, after controls for differences in general intelligence and in the other two variables. We hypothesise that children's mathematical reasoning will make a specific contribution to the prediction of KS results beyond what is predicted by the other factors. A positive result would provide the basis for a programme to promote children's mathematical reasoning with the aim to improve their mathematics achievement.
Separate scores for items within the mathematics assessments will be used to distinguish (a) additive and multiplicative reasoning; (b) reasoning about quantities and reasoning about relations; and (c) problems about extensive and intensive quantities. These will be used in analyses to investigate the extent of their relative power in the longitudinal prediction of maths and science attainment.
2. Is the development of some skills more important for progression than others?
There is a debate in education regarding the relative emphasis that should be given to computation and reasoning skills for later mathematics learning. It has also been suggested that spatial and visualisation skills are important for mathematics learning. The WISC contains sub-tests that allow for considering how arithmetic and spatial skills contribute to mathematics attainment.
There is also increasing interest in the role of attention in mathematics learning. The WISC subtest "Coding" is considered a measure of attention. Previous analysis of the ALSPAC data showed that the correlation between this sub-test and KS1 achievement was significant, though low. There are more specific measures of attention which will be used in this analysis.
3. Are there differences in the development of skills by gender, ethnicity, or socio-economic factors, such as parents' education or SES?
The dataset will be used for the analysis of these demographic variables considering both the impact of these variables at school entry and the possible augmentation of these effects if the home environment contains little academic incentive (e.g. books) and if the parents have low educational aspirations for the children.
Data from the teachers' questionnaires will be used to assess the effect of some school practices (streaming) and environment (number of pupils per class; number of students receiving free school meals; a specialist maths coordinator available) on students' mathematics progression.
4. How is development of understanding affected by children's self perception of their own ability in mathematics?
The ALSPAC measures of children's affective reactions to mathematics include questions on pupils' self-confidence, their liking for mathematics and its perceived usefulness, and their perception of the teacher's abilities and attitudes towards maths and teaching the subject. Different items were included at the different data collection points but it is possible to assess whether, according to different reports (i.e. by parents or by children), the students showed consistent liking, or not, for mathematics.
Some research has shown that pupils are reasonably accurate in identifying their position in their class as mathematics learners but their teachers' perceptions of them is just as important as their measured ability in influencing their self-perception as learners (Pretzlik, Olsson, Nabuco, & Cruz, 2003). Teachers' perceptions of their pupils' abilities in mathematics are influenced by the pupils' reading ability; the latter tend to be more accurate than their perceptions of the pupils' mathematics abilities. We need, therefore, to explore how pupils' abilities, their self-perceptions and their teachers' perceptions of them interact in the prediction of KS2-3 mathematics outcomes.
Final notes
In all of these analyses, we propose to test whether pupils' general ability and general self-confidence are better predictors of their attainment and later liking of maths than their specific mathematical reasoning capabilities and self-confidence. For this reason, measures of attainment in reading and in English, and self-confidence in and liking of English and Maths are required measures. It will also be necessary to analyse the data both including and excluding children with special needs (sensory, reading and language). The attainment of these groups of possible outliers could affect the results of the analyses.
The list of relevant variables is appended.
B688 - Childhood diet and adolescent depression - 16/08/2008
No outline received
B689 - The relationship between early speech and language development and later literacy - 13/08/2008
The most prominent explanation for specific reading difficulties is the phonological deficit hypothesis; that reading difficulties are caused by difficulties in accessing the phonological, or sound structure of speech. This makes it difficult for children to 'sound out' words in reading and spelling, and difficult to link spoken and written words in memory.
On the basis of this theory, it might be expected that children with early speech difficulties would be likely to show later literacy difficulties. In fact, many children with speech difficulties show good reading progress, and only a subgroup have literacy difficulties. Researchers have suggested various hypotheses to explain this fact. Most prominently, researchers have argued that only children with both speech and language difficulties are likely to go on to have literacy difficulties, and that therefore language difficulties are a more important risk factor than speech difficulties. This seems counter-intuitive given that speech is, on the face of it, more closely related to phonological processing. On this basis it seems that we need to consider carefully what we are measuring with standard language assessments.
Other researchers have argued that only children who show unusual or disordered speech errors are likely to go on to have literacy difficulties, or that only children who continue to have speech difficulties at the point at which they begin literacy instruction will be impaired. All of these alternative hypotheses can be examined using this dataset.
Previous studies have focused on group differences, and have generally used clinical samples referred through speech therapists or specialist schools. These methods will be subject to referral bias, and may underestimate the role of individual differences - for example, children with both speech and language difficulties tend to have more severe speech impairments than children with pure speech problems. A recent study of my own (Carroll & Myers, in preparation) showed that while children with both speech and language difficulties were more likely to have literacy difficulties, as previously suggested, language skills were not a significant predictor of growth in reading over time. This suggests that the link between the two could be explained by another third variable.
The ALSPAC study provides a way to investigate this possibility. Extensive background information is available on the families and children involved. There are repeated language assessments of a representative sample of children throughout the preschool years, together with clinical assessments of a smaller group at 24 months, 61 months and 8 years. These could be used to predict reading and spelling at 7, 9 and 12 years, and phonological skills such as nonword repetition, phoneme deletion and spoonerisms at the same time points. While the sample is considerably reduced by using measures from the 'children in focus' assessments, it remains a large sample in terms of clinical studies of this type.
The analyses will focus on using structural equation modelling and if necessary multiple regression to illustrate the relationships between the variables over time. Some group difference analyses examining those children in the sample showing significant difficulties will also be included. The measures requested for this analysis are shown on the following page
B749 - Association of rs1051730 maternal smoking genotype on child development - 12/08/2008
Maternal smoking is a known teratogen (1) and is associated with complications of pregnancy (2). Furthermore there is robust evidence that maternal smoking in pregnancy is causally associated with low birth weight in offspring (3;4). Observational studies have also reported associations of maternal smoking in pregnancy with various child outcomes such as increased obesity (5;6), reduced stature (7), lower cognitive development and behavioural problems (8;9) and higher blood pressure (10). However, results for these outcomes have been inconsistent and there is evidence that some of these associations reflect confounding by socioeconomic factors (10-13) rather genuine biological effects of intrauterine exposure to smoke.
We have explored associations of maternal smoking on offspring outcomes observationally in ALSPAC and have previously reported no association with child obesity (11), no association with child blood pressure (14) and an inverse association with child stature (15). We recently gained approval to study the relationship between maternal smoking and offspring cognition.
We would like to build on these existing observational analyses and explore the role of confounding further by using the rs1051730 genetic variant as a means of testing the causality of putative associations between maternal smoking in pregnancy and offspring outcomes.
It has recently been observed that rs1051730 genotype is associated with variations in smoking behaviour in pregnancy. An analysis using pooled data from ALSPAC and The Exeter Family Study of Childhood Health has shown that each additional copy of the rs1051730 risk allele is associated with higher odds ratios of continuing to smoke during the first trimester (Freathy et al., in press). Thus this genetic variant can be used to explore causality in relation to maternal smoking in pregnancy and offspring outcomes.
In sum, we would like to explore the associations of maternal rs1051730 genotype (associated with continued smoking behaviour in pregnancy) with:
1) child adiposity
2) child stature
3) child blood pressure
4) child cognition
For table of requested variables, please see attached.
Reference List
1. Dwyer JB, Broide RS, Leslie FM. Nicotine and brain development. Birth Defects Res C Embryo Today 2008;84:30-44.
2. Andres RL, Day MC. Perinatal complications associated with maternal tobacco use. Semin Neonatol 2000;5:231-41.
3. Sexton M, Hebel JR. A clinical trial of change in maternal smoking and its effect on birth weight. JAMA 1984;251:911-5.
4. Brooke OG, Anderson HR, Bland JM, Peacock JL, Stewart CM. Effects on birth weight of smoking, alcohol, caffeine, socioeconomic factors, and psychosocial stress. BMJ 1989;298:795-801.
5. Chen A, Pennell ML, Klebanoff MA, Rogan WJ, Longnecker MP. Maternal smoking during pregnancy in relation to child overweight: follow-up to age 8 years. Int J Epidemiol 2006;35:121-30.
6. Al Mamun A, Lawlor DA, Alati R, O'Callaghan MJ, Williams GM, Najman JM. Does maternal smoking during pregnancy have a direct effect on future offspring obesity? Evidence from a prospective birth cohort study. Am J Epidemiol 2006;164:317-25.
7. Lampl M, Kuzawa CW, Jeanty P. Prenatal smoke exposure alters growth in limb proportions and head shape in the midgestation human fetus. Am J Hum Biol 2003;15:533-46.
8. Julvez J, Ribas-Fito N, Torrent M, Forns M, Garcia-Esteban R, Sunyer J. Maternal smoking habits and cognitive development of children at age 4 years in a population-based birth cohort. Int J Epidemiol 2007;36:825-32.
9. Wakschlag LS, Pickett KE, Cook E Jr, Benowitz NL, Leventhal BL. Maternal smoking during pregnancy and severe antisocial behavior in offspring: a review. Am J Public Health 2002;92:966-74.
10. Brion MJ, Leary SD, Lawlor DA, Smith GD, Ness AR. Modifiable Maternal Exposures and Offspring Blood Pressure: A Review of Epidemiological Studies of Maternal Age, Diet and Smoking. Pediatr Res 2008;63:593-8.
11. Leary S, Davey Smith G, Rogers I, Reilly J, Wells J, Ness A. Smoking during pregnancy and offspring fat and lean mass in childhood. Obesity 2006;14:2284-93.
12. Gilman SE, Gardener H, Buka SL. Maternal smoking during pregnancy and children's cognitive and physical development: a causal risk factor? Am J Epidemiol 2008;168:522-31.
13. Batty GD, Der G, Deary IJ. Effect of maternal smoking during pregnancy on offspring's cognitive ability: empirical evidence for complete confounding in the US national longitudinal survey of youth. Pediatrics 2006;118:943-50.
14. Brion MJA, Leary SD, Davey Smith G, Ness AR. Similar associations of parental prenatal smoking suggest child blood pressure is not influenced by intrauterine effects. Hypertension 2007;49:1-7.
15. Leary S, Davey Smith G, Ness A. Smoking during pregnancy and components of stature in offspring. Am J Hum Biol 2006;18:502-12.
B748 - An investigation of breast cancer in the ALSPAC cohort - 12/08/2008
The aim of this project is to investigate the relationship between exposures during pregnancy and subsequent breast density, a strong determinant of breast cancer risk. The project will be undertaken within the Avon Longitudinal Study of Parents and their Children (ALSPAC) cohort. The specific objectives of the proposal are to investigate the relationship between each of two measures of breast density, described in detail below, and the following exposures:
i. Biological markers of the insulin-like growth factor (IGF) axis during pregnancy
ii. Nutritional intake during pregnancy
iii. Pregnancy weight patterns
iv. Diabetes or indications of hyperglycaemia in pregnancy
v. Blood pressure (BP), hypertensive disorder of pregnancy and pre-eclampsia
vi. Smoking during pregnancy
We also plan to investigate the relationship between IGF gene variants and IGF levels, with future plans to relate each of these to breast density.
The data collection phase of the project requires obtaining, digitising and analysing the mammograms of eligible mothers from the ALSPAC cohort. We will only include women who have a mammogram taken under the NHS Breast Screening Programme, which offers free mammography to women aged 50 to 70. As a result of the current study, we are not proposing to expose any woman to unnecessary radiation.
Eligibility criteria: The following women will be eligible to take part in the study; those who
i) have had a mammogram under the NHS Breast Screening Programme, or have one prior to the end of 2011 (eight months prior to study end);
ii) have not previously had a mammogram or MRI investigation of the breast
iii) consent to us accessing their mammograms (only requested from women aged 48 years or over, as per ethical approval);
iv) currently reside in Avon (this restriction is necessary, since we will only obtain mammograms from the Avon Breast Screening Programme)
Obtaining consent: Women who attend the Focus on Mothers clinic will be requested to consent to us obtaining and analysing their mammograms. Women who do not attend the clinic will be contacted by post and asked to give consent to us accessing their mammograms. Other than this, we will not have any further contact with the women.
Obtaining the mammograms: We will set up a flagging system, so that whenever a cohort member who has given us consent to access their mammogram attends screening, the research team will be informed. We will purchase an Array digitiser, and install it at the Avon Breast Screening Clinic (the Central Clinic). The research associate (RA) will then spend time at the Central Clinic each week, digitising the relevant films (both cranio-caudal and medio-lateral oblique images will be obtained), and transferring digital images to the coordinating centre. Dr Lis Kutt of the Central Clinic has writte a letter of collaboration agreeing to this.
Analysing breast density: Breast density will be performed in two ways: i) using a validated, computer-aided, threshold method, and ii) an automated volumetric method (SMF).
Exposure measurements: The following exposure data will be analysed.
From obstetric records: blood pressure and proteinuria in pregnancy; pregnancy weight measures; pregnancy diabetes / hyperglycaemia; offspring birthweight (from birth notification and/or obstetric data).
From questionnaire data: self-reported pre-pregnancy weight and waist/hip measures, (12 weeks' gestation); food frequency questionnaire (32 weeks' gestation); self-reported regular smoking during the 1st and 3rd trimesters; mother's weight at 8 weeks post-partum;
Biochemical measures: The earliest serum or plasma sample taken during pregnancy will be used to for analyses of: insulin, insulin-like growth factors (I and II) and relevant binding proteins (BP3).
Genetic measures: We plan to investigate 14 SNPs which have previously been demonstrated to be related to IGF-I or IGFBP-3 levels . Thirteen are listed below; one further relevant SNP (rs2854744) has already been genotyped. If other SNPs are identified from the literature duting the study period, we may request that analyses of further SNPs are performed. Funding to cover this eventuality will be requested in the initial grant proposal.