T cell receptor alpha chain polymorphisms in multiple sclerosis.

Numerous studies have implicated the major histocompatibility complex (MHC) class II alleles, DR2 and DQw1, as multiple sclerosis (MS) susceptibility loci, however, the involvement of other loci is implied by twin studies and the relative lack of haplotype sharing for MHC. To evaluate the role that the TCR alpha chain genes may have in MS susceptibility, three variable (V) alpha polymorphisms were examined for associations in MS patients. Genotype and allele frequencies were compared to four different control groups: unaffected siblings and parents of the MS patients, patients with insulin-dependent diabetes mellitus (IDDM) and healthy unrelated Caucasians. No significant differences in allele and genotype frequencies at these three loci were observed in the MS population compared to the control groups. In addition, we analysed the distribution of haplotype sharing in affected sibling pairs. Among 30 informative families, there was no significant increase in haplotypes shared by affected siblings over that expected based on random segregation. Our results do not support suggestions that germline TCR alpha chain genes contribute to genetic susceptibility in MS.