Characterization and distribution of HLA-B*5002 in a Spanish population sample

HLA-B45, in contrast to B44, does not show molecular polymorphism. We have found a group of Caucasian Spanish individuals, serologically typed as B45, showing an unexpected HLA-B12 PCR-SSO subtyping pattern. Complete coding region sequencing and B45 subtyping by PCR-SSO demonstrated that the B45 serologic specificity is constituted by two molecular alleles: B*4501 and B*5002. B*5002 is recognized by polyclonal and monoclonal allosera against B12 and B45, whereas it is not detected by B21, B49, or B50 reagents, providing a new example of poor correlation between serology and structure. B*5002 explains an important subset (18%) of the B45-positive individuals of the Spanish population studied, and almost half are included in a very infrequent haplotypic association, Cw6-B*5002-DRB1*0406-DQA1*03-DQB1*0402.