Segregation of polymorphic T-cell receptor genes in human families.

Polymorphism in the genes encoding the constant (C) region of the beta chain of the T-cell antigen receptor (CT beta, also called C beta) has been detected by molecular genotyping analyses. In initial screenings, a panel of restriction endonucleases was used to digest DNA samples from two individuals; the digested samples were subjected to Southern blot analyses using a CT beta probe. The enzyme Bgl II revealed restriction-fragment-length polymorphism in these samples and was subsequently used to test 59 individual members of eight different families. Polymorphic fragments detected in six of the families could be used to follow the segregation of T-cell receptor genes; in many cases maternal and/or paternal haplotypes could be assigned. All members of two additional families displayed a single CT beta hybridizing fragment. In one family the DNA sample from one of the children lacked an expected Bgl II restriction fragment. On the basis of analyses with other restriction enzymes, the most likely explanation is that the lymphoblastoid B-cell line used as a source of genomic DNA for this individual had rearranged or altered CT beta genes. Restriction-fragment-length polymorphisms used to discriminate CT beta haplotypes in families provide useful markers that will facilitate linkage studies and genetic analyses of T-cell function.