Characterization of a novel allelic variant in HLA-B*40 lineage, HLA-B*40:298:02, by cloning and sequencing.

A novel allelic variant in HLA-B*40 lineage, HLA-B*40:298:02, has been identified in an individual of Han ethnicity afflicted with nasopharyngeal carcinoma in Hunan province, southern China. Following polymerase chain reaction-Sanger sequence-based typing (PCR-SBT), this new variant was further confirmed by two distinct strategies of cloning and sequencing. HLA-B*40:298:02 differs from HLA-B*40:298:01 by a single synonymous cytosine substitution at nucleotide position 26 (T→C) in exon 3, which corresponds to codon 99 of the mature HLA-B mRNA molecule. This new allele has an estimated frequency of 0.0002, in about 2,500 sequence-based typed subjects from the same population.