To comprehensively examine the MICB gene polymorphism and identify its differences in Chinese Yao population from other ethnic groups, we investigated the polymorphism in the 5'-upstream regulation region (5'-URR), coding region (exons 2-4), and the 3'-untranslated region (3'-UTR) of MICB gene by using PCR-SBT method in 125 healthy unrelated Yao individuals in Guangxi Zhuang Autonomous Region. Higher polymorphism was observed in the 5'-URR, nine single nucleotide polymorphisms (SNPs) and a two base pairs deletion at position -139/-138 were found in our study. Only five different variation sites, however, were detected in exons 2-4 and three were observed in the 3'-UTR. The minor allele frequencies of all variants were greater than 5%, except for rs3828916, rs3131639, rs45627734, rs113620316, rs779737471, and the variation at position +11803 in the 3'-UTR. The first nine SNPs of 5'-URR and rs1065075, rs1051788 of the coding region showed significant linkage disequilibrium with each other. Ten different MICB extended haplotypes (EH) encompassing the 5'-URR, exons 2-4, and 3'-UTR were found in this population, and the most frequent was EH1 (23.2%). We provided several evidences for balancing selection effect on the 5'-URR of MICB gene in Yao population.
Keywords: Balancing selection; Gene diversity; Haplotype; MICB.
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