The genetic basis of autism has been well established. In addition to changes in DNA structure, other modifications, such as methylation or histone acetylation, may change gene expression in the absence of heritable mutations in DNA. Previous studies have indicated that environmental toxicants can gene expression through epigenetic mechanisms. Dr. Jiang has been working with a strain of mouse which shows mutations in both SHANK 3 and MTHFR, both implicated in autism spectrum disorder. He hypothesizes a link between folic acid and DNA methylation of SHANK3, producing abnormal gene expression. His lab will use this animal model to study whether administration of folic acid will increase 5-methylenetetrahydrofolate(5-MTHF) and cause DNA hypermethylation of synaptic protein like SHANK3. Changes in the methylation status of these genes would not change the structure, but may change the function of the gene such that differing levels of protein are produced, altering brain function and synaptic plasticity. Folic acid has been proven to reduce the incidence of major birth defects and is an important component of prenatal vitamins, however, this study will examine whether some mothers may be vulnerable to high doses of folic acid due to genetic variants of this pathway. What this means for people with autism: Because of the beneficial effects known to taking folic acid during pregnancy, this animal study will provide insight into the mechanisms by which folic acid affects the brain. It will also use new technologies to examine the role of epigenetics modifications of DNA in autism, and study the interaction between methylation of DNA and a gene implicated in ASD: SHANK3.