Aims - We aim to associate OXTR methylation level with measures of autistic like traits in cord blood derived from 1000 boys from the ALSPAC study.

Hypotheses - We hypothesize that (1) a relationship between methylation and traits exists and (2) that this relationship may depend on rs53576 genotype.

Rationale - Methylation of DNA exists in all human cells. While tissue-specific variation in DNA methylation has been observed, recent work indicates that, on the whole, methylation patterns are relatively conserved across tissue types within individuals. Published work from Connelly identified increased DNA methylation of a regulatory region of OXTR in ASD temporal cortex derived from Brodmann's area 41/42 that resulted in concomitant decreased transcription of OXTR. This brain region, a portion of superior temporal sulcus (STS), has been strongly implicated in social perception by virtue of its role in biological motion perception and theory of mind. Two of these ASD-specific DNA methylation changes (CpG sites -934 and -860) were also apparent in the blood of ASD individuals, and unpublished data from the PI indicates that methylation of CpG site -934 may be heritable. Importantly, this region of OXTR is not present on the current arrays used in recent large scale, methylome-wide studies in ASD; thus it is necessary to assay this region using other methods for replication. We recently replicated these methylation changes in a separate sample of male ASD individuals and their unaffected male siblings derived from the Simons Simplex collection. These data suggest that 1) increased DNA methylation of OXTR may lead to reduced OXTR gene expression in the ASD brain, 2) DNA methylation increases track with the ASD phenotype and 3) peripheral blood can be used a biomarker of brain methylation.

Data from the Connely lab establish an important relationship between measures of OXTR DNA methylation in the blood and perception of animacy in dynamic displays. The attribution of social meaning to these displays is consistently disrupted in ASD. Among typically developing individuals, viewing these displays recruits brain regions associated with mentalizing processes, including STS, temporal poles, and medial prefrontal cortex. Given the likely mediating role of oxytocin in social perception, we predicted that individual differences in OXTR methylation might affect response in these brain regions when viewing animate motion in dynamic displays. We found that higher levels of OXTR methylation predicted greater activity in STS and cingulate gyrus. Our results indicate that OXTR methylation may impact the degree to which individuals are sensitive to displays of animate motion. This perceptual sensitivity could be indicative of a social style that varies within the population and is compromised in ASD. Preliminary data in a larger sample of healthy Caucasians suggests that OXTR methylation may interact with a common functional variant along OXTR (rs53576) to influence the social brain. The A allele of rs53576 is related to decreased psychological resources, dispositional empathy and stress reactivity, as well as to structural and functional differences in oxytocinergic brain sites. We examined the relationship between OXTR methylation and response in anterior cingulate cortex to social attribution and emotional faces and find an inverse correlation based on rs53576 genotype.

Sample selection - 1000 male study participants weighted by autism like traits will be selected

Exposure Variables - NONE

Outcome Variables - Variables that fall under the catagories of communicative, social, and repetitive behavior; as in Table S2 [Steer, Golding, and Bolton, PLOS ONE 2010].

Confounding Variables - Although not considered a core requirement for the diagnosis of ASD, many children exhibit other traits such as learning difficulties, specific language impairment (SLI), ADHD, ODD/ CD, anxiety problems and special education needs.

Material Requested - 200 ng of DNA at 10ng/ul for genetic and epigenetic assays.