Tourette syndrome and autistic disorder: a significant relationship.

The histories of 10 children with autistic disorder or pervasive developmental disorder (PDD) cooccurring with familial Tourette syndrome (TS) are presented. Evidence from the histories of the patients and their relatives combined with other reports of cases of cooccurrence of TS and autism provides support for the hypothesis that TS may be responsible for cases of coocurrence of the disorders, contributes significantly to the etiological heterogeneity of autistic disorder and that a portion of cases of autism may actually be a result of homozygosity for the TS gene. In addition, the presence of affective disorders and autistic-like syndromes or mild disturbances of social relatedness in some of the pedigrees suggests the hypothesis that TS may be responsible for a subgroup of families with cooccurring affective and autistic disorders and for some cases of familial aggregation of autism-PDD.