This project will investigate the role of three separate factors in an animal model of autism spectrum disorder: a) genetic susceptibility, b) hormonal environment, and c) possible environmental triggers. A mouse model with a mutation of the reelin gene, implicated in autism spectrum disorders, will be studied after exposure to methyl and ethyl mercury. Both behaviors and neuropathological endpoints will be explored. Finally, the role of endogenous sex hormones will be examined by eliminating the testosterone "surge" around the time of puberty. The individual effects of each will be examined as well as the interaction of the three components (genetic liability, environmental exposure, hormonal influences) to determine gene x environment interactions. This study will use a unique design to study multiple factors in the etiology of autism spectrum disorder in a mouse model, isolating and combining factors which previously have been implicated in the pathophysiology and behavioral phenotype.