Genome-wide DNA methylation profiles in post-mortem autistic brains

Previous studies indicate that autism has a strong genetic component; however, the underlying genetic mechanisms remain unclear. Recently, it was reported that genetic heritability is lower than previously estimated, and that environmental factors have a greater influence on the development of autism spectrum disorder (ASD). Epigenetic processes such as DNA methylation are considered to be at the interface of genetic and environmental factors. Additionally, two well-characterized epigenetic processes, parental imprinting and X chromosome inactivation, are involved in several conditions that mimic autism spectrum disorders, such as Rett and Fragile-X syndromes, suggesting that epigenetic processes may play an important role in the pathophysiology of autism. We investigated genome-wide DNA methylation profiles in post-mortem brain tissue from individuals with autism using the Infinium HumanMethylation450 BeadChip (Illumina), which includes CpG sites of intragenic and intergenic regions. We investigated genome-wide DNA methylation profiles in the dorsal raphe (DR) region of the post-mortem brain from male individuals with autism as well as normal controls. The Autism Tissue Program (Princeton, New Jersey; http://www.autismtissueprogram.org), National Institute of Child Health and Development Brain and Tissue Bank for Developmental Disorders (Baltimore, Maryland; http://medschool.umaryland.edu/btbank/) and the Harvard Brain Tissue Resource Center (Belmont, Maryland; http://www.brainbank.mclean.org/) provided us with frozen post-mortem brain tissues from the DR regions (5 with autism and 7 control subjects).