Gene × Environment interactions in autism spectrum disorders: role of epigenetic mechanisms.
Several studies support currently the hypothesis that autism etiology is based on a polygenic and epistatic model. However, despite advances in epidemiological, molecular and clinical genetics, the genetic risk factors remain difficult to identify, with the exception of a few chromosomal disorders and several single gene disorders associated with an increased risk for autism.Furthermore, several studies suggest a role of environmental factors in autism spectrum disorders (ASD).
First, arguments for a genetic contribution to autism, based on updated family and twin studies, are examined.
Second, a review of possible prenatal, perinatal, and postnatal environmental risk factors for ASD are presented.
Then, the hypotheses are discussed concerning the underlying mechanisms related to a role of environmental factors in the development of ASD in association with genetic factors. In particular, epigenetics as a candidate biological mechanism for gene × environment interactions is considered and the possible role of epigenetic mechanisms reported in genetic disorders associated with ASD is discussed.
Furthermore, the example of in utero exposure to valproate provides a good illustration of epigenetic mechanisms involved in ASD and innovative therapeutic strategies.
Epigenetic remodeling by environmental factors opens new perspectives for a better understanding, prevention, and early therapeutic intervention of ASD.