TCRBV 12 genes are polymorphic but the protein products encoded by each gene are conserved

The human TCRBV gene complex contains three BV12 genes and all are polymorphic. There are two alleles of BV12S4; one allele contains a stop codon in the coding region which precludes its expression. There are four alleles of BV12S2 and two alleles of BV12S3 genes; however, the substitutions present in both genes are conservative. Although allelic variants exist for each of the three BV12 genes, only one protein product is encoded by each gene.