Identification of a variable number tandem repeat region in the human T cell receptor alpha-delta (TCRAD) locus

A number of different polymorphisms have been observed in coding as well as in non-coding regions of T cell receptor (TCR) genes. We report the identification and characterization of a highly polymorphic locus in the 3' noncoding region of the human T cell receptor alpha/delta (TCRAD) on chromosome 14. In 202 unrelated individuals, ten different alleles were distinguished by polymerase chain reaction (PCR) and a heterozygosity rate of 64% was calculated. Sequence analysis revealed that this polymorphic region consists of 10 bp imperfect repeat units and represents a variable number tandem repeat region (VNTR). Stable Mendelian inheritance of this novel polymorphic marker was proven in four families. The localization of this VNTR polymorphism in the TCRAD locus should make it a useful system for linkage analysis in immunological disorders with a known role of TCRAD.