MICA-HLA-B haplotype diversity and linkage disequilibrium in a population of Jewish descent from Majorca (the Balearic Islands)

The major histocompatibility complex class I chain-related A (MICA) gene is located 46 kb centromeric of human leukocyte antigen (HLA)-B and is highly polymorphic, similar to HLA genes. This allelic variation may influence the affinity of MICA molecules to their receptor on natural killer, γδ T and CD8+ T cells, NKG2D, and the immune response to organ transplantation and disease susceptibility. In the present study, we typed MICA and HLA-B polymorphisms in 95 individuals from a population of Jewish descent (Chuetas) and 195 individuals of Caucasian origin from Majorca (the Balearic Islands). MICA*008, -*004, and -*002 were the most common alleles and accounted for 53 and 60% in Chuetas and Majorcans, respectively. Other common alleles (frequency >5%) were MICA*016, -*009, -*012, -*007, and -*017 in Chuetas and -*009, -*001, and -*018 in Majorcans. We also studied two-locus haplotype diversity and linkage disequilibrium (LD). Both populations presented haplotypes with significant LD that were shared by other Caucasians populations, but we reported particular haplotypes in the Chueta group: MICA*002–HLA-B*38, MICA*016–HLA-B*35, MICA*012–HLA-B*55, and MICA*017–HLA-B*57. These haplotypes were not reported in other studies at high frequencies. In conclusion, the Chueta population presents a particular genetic pool but has affinities with the host population.