In this study, human leukocyte antigen (HLA)-E allelic typing was performed for 690 individuals from two southern Chinese Han populations (Hunan Han and Guangdong Han) and two northern Chinese populations (Inner Mongolia Han and Inner Mongolia Mongol) using polymerase chain reaction-sequence-specific priming (PCR-SSP) method. Our data showed that (1) HLA-E*01:01 and HLA-E*01:03, but not E*01:04 allele, were detected in the four populations, HLA-E distribution differed significantly between each of the two southern Chinese Han populations and the Inner Mongolia Mongol population, and between Hunan Han population and Inner Mongolia Han population; (2) HLA-G*01:05N-A*30-E*01:01-C*06-B*13:02-DRB1*07 was a conserved extended haplotype in the Chinese Han populations; (3) five HLA-A-E haplotypes showed significant linkage disequilibrium (LD) in at least one population, including HLA-A*02-E*01:03 in populations except for the Inner Mongolia Mongol group, HLA-A*01-E*01:01 and HLA-A*30-E*01:01 in the Hunan Han and the Inner Mongolia Han populations, HLA-A*33-E*01:01 in the two southern Chinese Han populations and HLA-A*03-E*01:03 in the Inner Mongolia Mongol group; and (4) Ewens-Watterson homozygosity test showed a trend for balancing selection at the HLA-E locus in each of the four populations. Our data unraveled the peculiarity in terms of HLA-E allelic and haplotypic repertoire in four main ethnic groups in Mainland China, findings shown here are valuable for future studies of the potential role of HLA-E in allogeneic organ transplantation and HLA-linked disease association in related ethnic groups.

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Currently, there is a lack of information on polymorphism of human leucocyte antigen-F (HLA-F) gene in ethnically diverse human populations. In this study, HLA-F allelic typing was performed for 690 individuals representing two southern Chinese Han populations (Hunan Han and Guangdong Han) and two northern Chinese populations (Inner Mongolia Han and Inner Mongolia Mongol), using polymerase chain reaction-sequence-specific priming (PCR-SSP) and PCR-sequencing methods. Our results showed that (i) HLA-F*01 : 01 predominated in each population with a frequency >0.94 and HLA-F*01 : 03 was relatively more common in the two northern Chinese populations with a frequency of approximately 0.05; (ii) both geographical and ethnical factors are related to HLA-F allelic distribution, as evidenced by the significant difference in HLA-F allelic distribution between the Hunan Han population and the two northern Chinese populations; (iii) significant linkage disequilibrium (LD) was observed for haplotype HLA-A*03-F*01 : 03 in three populations. In most cases, this haplotype extended to HLA-E*01 : 03; and (iv) Ewens-Watterson homozygosity statistic at the HLA-F locus did not depart significantly from expectation in each of the four populations. Our data revealed a low level of HLA-F allelic variation in Chinese populations, suggesting that HLA-F gene may have existed before some of the HLA-A polymorphism and have been evolving under neutrality.

In this study, the 5' promoter region of MHC class I chain-related gene B (MICB) was investigated in 104 healthy, unrelated Han individuals recruited from northern China, using polymerase chain reaction (PCR)-sequencing methodology. Fifteen variable sites were detected, which showed a mosaic pattern of significant global linkage disequilibrium (LD). Eleven different 5' promoter haplotypes were identified. MICB 5' promoter haplotype-9 carrying CT deletion at positions -139/-138, which is associated with decreased MICB promoter activity, was present in 26.9% of MICB alleles and was linked to MICB*002:01, MICB*008, and MICB*014 in this population. In addition, rs3828913 (position -176) and rs3828914 (position -152) were located adjacent to HSRE and GC box in MICB promoter, respectively. Sixteen extended haplotypes (EH) incorporating the MICB 5' promoter and MICB coding region were observed in this population, eight of which were in significant LD. Phylogenetic analysis of 5' promoter refined MICB sub-lineage structure indicated that MICB*005:02, the most common MICB allele, consists of five sub-lineages. Ewens-Watterson homozygosity statistics at MICB 5' promoter region were consistent with neutral expectations. Our study has shed new insight into MICB genetic variation at population level, suggesting that binding sites for transcription factors in MICB promoter could be interrupted by polymorphisms within this region, resulting in allele-specific regulation. The data will facilitate the understanding of regulation of MICB gene transcription, and will inform studies of evolution of the major histocompatibility complex (MHC) gene complex.

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OR, 3.18; 95% CI, 1.54-6.56; TC vs. TT: OR, 1.65; 95% CI, 1.27-2.03). However, no overall association was observed between the other two polymorphisms of eNOS (G894T and 4a4b) and male infertility. Stratified analysis showed that significantly strong association between T786C polymorphism and semen quality was present in all three types of male infertility (azoospermia, oligozoospermia and asthenozoospermia). In the subgroup analysis based on ethnicity, both T786C and 4a4b could influence the risk of male infertility in Asian and Caucasian. Further studies of polymorphisms of eNOS with their biological functions are needed to understand the role in the development of male infertility.