Characterization of 3'untranslated region (3'UTR) of the MICB gene

In this study, the 3'untranslated region (3'UTR) of MHC class I chain-related gene B (MICB) were investigated in 104 healthy, unrelated Han individuals recruited from northern China, using PCR-sequencing method. Seven polymorphic sites were detected including a 2-bp deletion/insertion, a 6-bp deletion/insertion and 5 SNPs. Seven different 3'UTR alleles were identified with frequencies ranging from 0.0048 to 0.7981. MICB(∗)005:02, the most frequent allele in this population, exhibited significant linkage disequilibrium (LD) with UTR1; MICB(∗)004:01, which was also relatively common in this population, showed strong LD with both UTR2 and UTR3 alleles. Analysis for targets of miRNAs revealed that miRNA hsa-miR-4768-5p, whose seed region binds to positions 82-88 of MICB 3'UTR, encompasses the +11800 A/G polymorphism. Ewens-Watterson homozygosity statistics at MICB coding and 3'UTR regions were consistent with neutral expectations. Phylogenetic analysis demonstrated the existence of two main MICB lineages. Our results provided for the first time the data of genetic variation in the 3'UTR of MICB gene in human populations. The findings are valuable for future studies of the mechanisms underlying MICB post-transcriptional regulation, the potential role of regulatory region of MICB gene in disease susceptibility in related ethnic groups, and will inform studies of evolution of the MHC gene complex.