Strong association of the third hypervariable region of HLA-DR beta 1 with autism.

We reported that the major histocompatibility complex (MHC) including the null allele of the C4B gene and the extended haplotype B44-C30-DR4 is associated with autism. We report now that the third hypervariable region (HVR-3) of certain DR beta 1 alleles have very strong association with autism. The HVR-3 of DR beta 1* 0401 or the shared HVR-3 alleles DR beta 1* 0404 and DR beta 1* 0404 and DR *0101, was expressed on extended haplotypes in 23 of 50 (46%) autistic subjects as compared to only 6 of 79 (7.5%) normal subjects. Another HVR-3 sequence, the DR beta 1* 0701 allele, was carried on extended haplotypes in 16 (32.0%) of the autistic subjects as compared to 8 (10.1%) of the normal subjects.