What research has been done in autism to determine a possible genetic etiology?
Although the adoption study method has not been used in autism, several twin studies have been completed. One such study showed that autism as well as a set of milder impairments (e.g., language delay) occur more often in MZ than in DZ co-twins of a child with autism (Folstein & Rutter, 1977). A more recent twin study has confirmed this finding, concluding that the impairment in the non-autistic co-twins may involve social, language, and/or repetitive/stereotyped behaviors and interests (LeCouteur et al., 1996). Family history and family studies have found that autism, as well as specific types of language, social characteristics, psychiatric (e.g., depression, anxiety), and personality features occur more often in adult siblings and parents of individuals with autism than in controls (Bailey et al., 1996; Landa et al., 1997; Piven et al., in press). This information is now being used to inform linkage studies of autism. What is a linkage study and is this methodology being used in aut
