Characterization of a new HLA-B*38 allele (B*3803) in a Spanish Caucasian individual which is closely related to the Oriental B*38021 and B*39021 alleles

The broad HLA-B16 serologic specificity is divided into B38 and B39 splits associated to Bw4 and Bw6, respectively. Differential serologic variants have been defined for several molecular subtypes of B39 and for B38. We found a Spanish Caucasian individual carrying a B16 BW4-associated antigen which was not recognized by reagents against B16 splits. Sequencing analysis showed a new B16 subtype termed B*3803. HLA class I sequence-based typing (SBT) analysis demonstrated that B*3803 cosegregates with A*2608 and Cw*1203 forming a common Caucasian haploytpe. Sequence comparison with B*38 and B*39 subtypes evidences that although B*3803 is close related to B*3802, it only differs from B*39021 by six clustered nucleotide position in the Bw4/Bw6 motif, and strongly suggests that B*3803 could have evolved from or be the ancestral gene of the oriental-associated B*3802 and B*39021 alleles. However, more complex patterns of genetic events should be considered due to that Caucasian background of the B*3803 individual an its associated haplotype.