HLA-B*8202 identified in a Caucasoid potential bone marrow donor

Sequence analysis of HLA class I alleles has continued to reveal the true e xtent of polymorphism, particularly for B locus alleles. This diversity can arise through reshuffling of polymorphic sequences generated by point muta tion, resulting in interallelic recombination or intergenic recombination ( 1). Here we describe a new B-locus allele, B*8202, which is structurally mo st similar to B*8201, having only one nucleotide difference in exon 3 at nu cleotide 557, resulting in an amino acid change of aspartic acid to glycine at residue 162. Glycine is the consensus amino acid for B locus alleles, w hich suggests that B*8202 is older than B*8201 in evolutionary terms. B*820 1 was found to be a hybrid of B*4501 and B*5602 that may have arisen throug h recombination events, explaining the serological patterns observed with t hese allotypes. The importance of high-resolution typing is emphasised here as routine typing suggested the presence of B*8201 and the new variant all ele may have been missed had it not been typed further by sequence-based ty ping.