Polymorphic markers of human T-cell receptor alpha and beta genes. Family studies and comparison of frequencies in healthy individuals and patients with multiple sclerosis and myasthenia gravis.

Polymorphic markers for the human T-cell receptor (TcR) genes are described. With a TcR beta-chain probe, polymorphic allelic fragments of 5.4 and 1.8 kb were detected in KpnI digests, and fragments of 12.5 and 11.5 kb were seen in the BglII digests. Polymorphism in alpha chain genes was observed in TaqI-digested DNA samples with bands at 10.2 and 6.2-2.1 kb. Mendelian codominant inheritance for all three polymorphisms was confirmed in family studies. The gene frequencies for these alleles were determined in a sample of 70 normal unrelated Caucasian individuals, and were shown to be in Hardy-Weinberg equilibrium. There were no significant differences in the frequency of these polymorphic alpha and beta alleles between patients with multiple sclerosis and patients with myasthenia gravis as compared to a panel of control healthy individuals.