By Daniel B. Campbell
American Journal of Psychiatry
March 2015
Autism spectrum disorder includes a deficit in social communication as one of its underlying elements or endophenotypes. Endophenotypes are elements of a disorder that are thought to arise from a specific cause, usually a genetic variation. They are generally more widespread in families than the disorder itself, with many nonaffected members of the families expressing the endophenotype but not reaching criteria for the full clinical diagnosis. An endophenotype that is scored quantitatively in all family members has much more power to show genetic linkage in the family than the diagnosis alone, which occurs in only some of the family members. In this issue of the Journal, Lowe et al. hypothesized that social communication deficits might serve as the endophenotype that would provide sufficient power to identify regions with inherited genetic variants that contribute to autism. Most of the genetic risk for autism is inherited, yet DNA sequencing projects have focused mostly on de novo (i.e., not inherited) genetic variants found in individuals with autism…
