Genetic Variation of the Serotonin System and Cortical Enlargement in Autism

 Identifying the genetic basis of the cortical abnormalities in autism may help elucidate the genetic basis of autism itself. But while the volume of both genotyping and brain imaging data in autism is rapidly expanding, studies integrating these modalities are still modest in size, necessitating careful selection of genetic variants for study. We examined the effect of variation in two serotonin genes (SERT and MAOA) on brain size in children with autism and found that, in both genes, polymorphisms associated with diminished serotonin metabolism were associated with increased cortical size. Strengths and limitations of this type of research approach, as well as challenges faced by the attempt to integrate genetic with brain imaging data, will be discussed.