Autism Linked to Epigenetic Differences in Monozygotic Twins

Could these differences become targets for prevention or treatment?

Even monozygotic (MZ) twins raised together differ in their epigenome. These investigators hypothesized that CpG sites in MZ twins who both had autism spectrum disorder (ASD) would show less differential methylation than within twin pairs who were discordant for ASD.

The participants were 50 MZ pairs; 34 were discordant and 16 were concordant for ASD or low autism scores. Diagnosis occurred at age 8 years, with a reliable scale administered to parents. This scale has three domains (social behavior, repetitive behavior, and communication) and severity ranges. Peripheral blood samples obtained at age 15 were used to assess CpG methylation.

Differential methylation was significantly greater within discordant pairs than within concordant pairs. Significantly greater differential methylation was associated with discordant scores in each domain and with greater severity on each domain. Some differentially methylated genes were similar across twin pairs; others were novel to particular twin pairs. Some differentially methylated genes conferred an increase in ASD risk in previous genetic studies.

CITATION(S):

Wong CCY et al. Methylomic analysis of monozygotic twins discordant for autism spectrum disorder and related behavioural traits. Mol Psychiatry 2013 Apr 23; [e-pub ahead of print].