INCREASED FREQUENCY OF THE EXTENDED OR ANCESTRAL HAPLOTYPE B44-SC30-DR4 IN AUTISM

Autism likely results from several different etiologies or a combinati on of pathological mechanisms. Recent studies suggest that this disord er may be associated with immune abnormalities, pathogen-autoimmune pr ocesses and perhaps the major histocompatibility complex (MHC). In a p reliminary study we found that 22 autistic subjects had an increased f requency of the extended or ancestral MHC haplotype B44-SC30-DR4. The current study attempted to confirm this observation by studying 23 add itional randomly chosen autistic subjects, most of their parents and 6 4 unrelated normal subjects. In agreement with earlier findings B44-SC 30-DR4 was associated with autism. In combining the data from the orig inal and current studies, B44-SC30-DR4 or a substantial fragment of th is extended haplotype was represented in 40% of the autistic subjects and/or their mothers as compared to about 2% of the unrelated subjects . It is concluded that one or more genes of the MHC is (are) involved in the development of some cases of autism.