Repertoire and organization of human T-cell receptor alpha region variable genes

A contig of YAC, PAC, and cosmid clones that spanned the human T-cell receptor alpha variable (AV) gene region on chromosome 14 was assembled. PCR primers corresponding to the members of 32 different subfamilies were used to map AV genes on the genomic clones. Nucleotide sequencing of PCR products derived from different genomic clones was used to discriminate between related AV gene segments that coamplified. The presence of individual AV gene segments on genomic clones was further confirmed by hybridization both to clones and to human genomic DNA from several unrelated individuals. These results suggest that the T-cell receptor alpha (TCRA) region in humans contains at least 46 distinct AV gene segments that can be grouped into 32 subfamilies based on nucleotide homology. Several subfamilies appear to contain additional members detectable by hybridization that do not map to chromosome 14.