MICA polymorphisms and haplotypes with HLA-B and HLA-DRB1 in Koreans

Major histocompatibility complex (MHC) class I chain-related gene A (MICA) is located within the human MHC, centromeric to HLA-B and telomeric to HLA-DRB1. The location of MICA in the MHC indicates the presence of linkage disequilibrium with human leukocyte antigen (HLA). Like HLA, MICA is highly polymorphic; however, the information available for MICA polymorphisms is not as comprehensive as that for HLA polymorphisms. We estimated the allelic frequencies of MICA and haplotypes with HLA-B and HLA-DRB1 at high-resolution in a population of 139 unrelated Korean individuals by applying the newly developed method of sequence-based typing (SBT). A total of 17 MICA alleles were identified. The most frequent allele was MICA*010 (19.4%), followed by alleles *00201 (17.6%), *00801 (14.7%), *01201 (9.4%), *004 (8.3%) and *049 (7.9%). The most common two- and three-locus haplotypes were HLA-B*1501-MICA*010 (10.4%), MICA*010-HLA- DRB1*0406 (5.8%) and HLA-B*1501-MICA*010-HLA-DRB1*0406 (5.8%). This is the first study to provide such high-resolution information on the distribution of haplotypes comprising MICA, HLA-B and HLA-DRB1 in Korean individuals, a level of resolution made possible by use of the SBT method. The results of this study should help determine the mechanisms underlying diseases associated with MICA polymorphisms in Korean individuals.