HLA-B*4021: hybrid linking the B15 and B40 families

Twenty alleles encoding molecules with the B60 or B61 serologic specificity have been reported thus far. This study characterized a new allele encoding a molecule exhibiting partial serologic reactivity with B15- and B40-related alloantisera from unrelated Korean individuals. Based on the DNA sequence, it appears that the novel allele has a sequence identical to some of alleles in B*15 family including B*1501 in exon 2. The sequence in exon 3, however, is identical to alleles in the B*40 family (B*4001/07/10/12) and B*4803. This implies that the novel allele, B*4021, has evolved by a reciprocal gene recombination involving members of these two families. The haplotype associated with B*4021 is likely to be A11-Cw4-B*4021-DRB1*04-DRB4*01-DQA1*03-DQB1*0301 .