Sequencing and PCR-RFLP analysis of HLA-DMB polymorphism in Japanese.

Abstract

Novel class II genes, DMA and DMB have been mapped recently between the DQ and DP genes within the HLA class II region. It has been suggested that DM molecule functions at an intracellular site to promote class II molecule-peptide association in the antigen presentation pathway. Genetic polymorphisms in the DMB gene are concentrated in the 3rd exon coding theβ2 domain and 4 alleles (DMB* 0101-0104) have been so far identified in Caucasian populations. In this study, we have analyzed genetic polymorphism in a Japanese population by direct automated sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and could recognize DMB* 0101 (48.0%) , DMB* 0102 (20.0%) , and DMB* 0103 (24.5%). No DMB* 0104 was detected. Further, a new allele (DMB* 595new) containing Val and lie at amino acid positions 50 and 85, respectively was identified in a B-lymphoblastoid cell line of Japanese origin. DMB* 0101 and DMB* 0102 were found to he in linkage disequilibria with DPB1* 0402 and DRB1* 1502, and with DRB1* 1101 and DRB1* 1405, respectively. HLA-DMB typing using the PCR-RFLP method estahlished in this study will he useful to analyze the BLA class II-disease association and also to perform the HLA matching for donor selection in unrelated transplantation.