Determination of the 3'UTR region of HLA-B*53:01:03 sequence by next generation sequencing

The 3'UTR of the HLA-B*53:01:03 allele has been determined by next generation sequencing.

Characterization of the novel KIR3DL1*0150213 and KIR3DL1*112 alleles using sequence-based typing

KIR3DL1*0150213 differs from KIR3DL1*0150211 at 15 nucleotide positions. KIR3DL1*112 differs from KIR3DL1*03101 at 19 nucleotide substitutions.

Strong association of SLC1A1 and DPF3 gene variants with idiopathic male infertility in Han Chinese

Male infertility is a multifactorial syndrome encompassing a wide variety of disorders. In recent years, several genome-wide single-nucleotide polymorphism (SNP) association studies (GWAS) have been performed on azoospermia and/or oligozoospermia in different populations including two GWAS on nonobstructive azoospermia in China; however, the association of SNPs with idiopathic male infertility, especially asthenozoospermia and oligozoospermia, and their correlation with semen parameters are still not clear. To investigate genetic variants associated with idiopathic male infertility (asthenozoospermia, oligozoospermia, and oligoasthenozoospermia) in Chinese Han people, 20 candidate SNPs were selected from GWAS results and genotyped using the Sequenom MassARRAY assay. A total of 136 subfertile men and 456 healthy fertile men were recruited. rs6476866 in SLC1A1 (P = 1.919E-4, OR = 0.5905, 95% CI: 0.447–0.78) and rs10129954 in DPF3 (P = 0.0023, OR = 2.199, 95% CI: 1.311–3.689) were strongly associated with idiopathic male infertility. In addition, positive associations were observed between asthenozoospermia and rs215702 in LSM5 (P = 0.0016, OR = 1.479, 95% CI: 1.075–2.033) and between oligoasthenozoospermia and rs2477686 in PEX10 (P = 0.0011, OR = 2.935, 95% CI: 1.492–5.775). In addition, six SNPs (rs215702 in LSM5, rs6476866 in SLC1A1, rs10129954 in DPF3, rs1801133 in MTHFR, rs2477686 in PEX10, and rs10841496 in PED3A) were significantly correlated with semen quality alterations. Our results suggest that idiopathic male infertility in different ethnic groups may share the same mechanism or pathway. Cohort expansion and further mechanistic studies on the role of genetic factors that influence spermatogenesis and sperm progressive motility are suggested.

Correlation between natriuretic peptide receptor C (NPR3) gene polymorphisms and hypertension in the Dai people of China

Hypertension affects one-fifth of the world population. Genome-wide association studies (GWAS) have identified several single nucleotide polymorphisms (SNPs) that correlated with hyper-tension in large samples. However, the genetic mutations leading to hypertension might differ among various populations, as they have different origins and are subjected to different environmental pressures. Therefore, additional studies are urgently needed to verify the GWAS findings across different populations. This study focused on the natriuretic peptide receptor C gene (NPR3), one of the hypertension-positive genes identified in a GWAS of an East Asian population. The correlation analysis between NPR3 and hypertension was replicated in 450 Chinese Dai (235 patients vs 215 controls) and 484 Chinese Mongolian (211 patients vs 273 controls) individuals. The positive SNP identified by GWAS analysis and three other tag SNPs representing the NPR3 linkage disequilibrium (LD) block regions were selected for genotyping. The results revealed that the rs1173766 polymorphism was associated with the occurrence of hypertension (χ(2) = 6.87, P = 0.0088), and that the T allele should be protective in the Dai ethnic group. Consider-ing a close LD block at the 3' end of the NPR3 gene in the East Asian population, we speculate that there might be a mutation in the last five exons or the 3' untranslated region of NPR3 that could change the structure or expression of the NPR3 gene. However, in the Mongolian ethnic group, these SNPs were not associated with the incidence of hypertension, suggesting population heterogeneity for the genetic factors that contribute to hypertension.

[Distribution of HLA-G 14 bp insertion/deletion polymorphism and their associations with HLA-A alleles in four Chinese ethnic groups]

Recently, a 14 bp insertion/deletion polymorphism (+14 bp/-14 bp) in exon 8 of the human leucocyte antigen-G (HLA-G) gene has been widely recognized to associate with recurrent miscarriage, autoimmune diseases, hepatocellular carcinoma and other diseases. Our previous studies have shown the distribution characteristics of linguistic family for HLA-G 14 bp insertion/deletion in different ethnic groups. In the present study, we investigated the distribution of HLA-G 14 bp insertion/deletion polymorphism and their subsequent associations with HLA-A alleles in Tu, Yugu, Lisu and Nu ethnic populations based upon the HLA-A genotyping data. Our results showed that the frequencies of the 14 bp insertion/deletion polymorphism were diverse in these four populations while that in the same linguistic subfamily was similar. The significant difference in different linguistic subfamily except for Han and Mongolian language subfamily was identified. In addition, the 14 bp insertion was found to associate with HLA-A alleles in different ethnic populations.

[Polymorphic Alu insertions and their associations with HLA I alleles in Yugu and Zhuang ethnic populations]

Many studies have show that the structurally polymorphic Alu insertion within HLA class I region are useful tools for investigating the origin, evolution and recombination of HLA class I progenitor haplotypes and gene diversity in different ethnic populations. In the present study, we determined the frequencies of HLA-Alus (i.e., AluMICB, AluTF, AluHJ, AluHG, and AluHF) in Zhuang and Yugu ethnic populations at first. Then, combined with HLA genotyping data, we studied associations between HLA-Alus and HLA-A alleles in Zhuang, Yugu, Bulang, Dai, and Hani ethnic populations. Our results showed that (1) the frequencies of five HLA-Alus were 1.5%~35.8% and 9.2%~34.8% in Zhuang and Yugu, respectively; and (2) the results of association between HLA-A alleles and HLA-Alu showed strong association between AluHG insertion and HLA-A 02 subtypes in all populations, association between AluHJ insertion and HLA-A 2402 in all populations, and association between AluHJ insertion and HLA-A 1101, -A 2407 in Bulang. The present study suggested that the distribution of HLA-Alus as well as the associations between HLA-Alus and HLA class I alleles are variable in different ethnic populations. HLA Alus alone or together with the HLA class I alleles are informative genetic markers for the identification of HLA class I allele and variation of haplotype lineages in different populations.

[Variation of CAG repeats in coding region of ATXN2 gene in different ethnic groups]

Toinvestigate CAG repeats variation of ATXN2 gene coding region in six ethnic groups that live in comparatively different environments, to evaluate whether these variations are under positive selection, and to find factors driving selection effects, 291 unrelated healthy individuals were collected from six ethnic groups and their STR geneotyping was performed. The frequencies of alleles and genotypes were counted and thereby Slatkin's linearized Fst values were calculated. The UPGMA tree against this gene was constructed. The MDS analysis among these groups was carried out as well. The results from the linearized Fst values indicated that there were significant evolutionary differences of the STR in ATXN2 gene between Hui and Yi groups, but not among the other 4 groups. Further analysis was performed by combining our data with published data obtained from other groups. These results indicated that there were significant differences between Japanese and other groups including Hui, Hani, Yunnan Mongolian, and Inner Mongolian. Both Hui and Mongolian from Inner Mongolia were significantly different from Han. In conclusion, the six ethnic groups had their own distribution characterizations of allelic frequencies of ATXN2 STR, and the potential cause of frequency changes in rare alleles could be the consequence of positive selection.

CAG-repeat variant in the polymerase γ gene and male infertility in the Chinese population: a meta-analysis

Several studies have reported a relationship between the length of the CAG-repeat in the polymerase γ (POLG) gene and male infertility. However, other studies have not reproduced this result. In our study, the POLG-CAG-repeat length was analyzed in 535 healthy individuals from six Chinese Han populations living in different provinces. The frequencies of 10-CAG alleles and genotypes were high (97.38 and 94.13%, respectively), with no significant difference among the six Chinese Han populations. Furthermore, we determined the distribution of the POLG-CAG-repeat in 150 infertile men and 126 fertile men. Our study suggested that the distributions of POLG-CAG-repeat alleles and genotypes were not significantly different between infertile (95.67 and 92.67%, respectively) and fertile men (97.22 and 94.44%, respectively). In a subsequent meta-analysis, combining our data with data from previous studies, a comparison of the CAG-repeat alleles in fertile versus infertile men showed no obvious risk for male infertility associated with any particular allele (pooled odds ratio (OR)=0.94; 95% confidence interval (CI): 0.60-1.48). The significance level was not attained with any of the following genetic models: homozygote comparison (not 10/not 10 versus 10/10: OR=1.34; 95% CI: 0.66-2.72), heterozygote comparison (10/not 10 versus 10/10: OR=1.04; 95% CI: 0.78-1.38), dominant model comparison (not 10/not 10+10/not 10 versus 10/10: OR=1.08; 95% CI: 0.79-1.47) and recessive genetic comparison (not 10/not 10 versus 10/not 10+10/10: OR=1.31; 95% CI: 0.68-2.55). In conclusion, there is no significant difference of the frequencies of POLG-CAG-repeat variants among six Chinese Han populations, and this polymorphism may not be associated with Chinese male infertility. On the basis of a meta-analysis, there is no obvious association between CAG-repeat variants of the POLG gene and male infertility.

[Genetic relationships among six Chinese populations revealed by analysis of 30 autosomal STRs]

30 autosomal STRs of 6 Chinese populations (Bai, Naxi, Tu, Sala, Han in Shandong, She) were amplified by multiplex PCRs using fluerescein-labelled primers. Shriver's Dsw was estimated on the basis of the results of the genescanning and genotyping after running unnatural PAGE of the PCRs' products on ABI 377 sequencer. Phylogenetic trees were constructed by using Neighbor-Joining and UPGMA method based on Dsw, and then the genetic relationships among them were analyzed referring to some relative informations. Our results indicated that the genetic distance between Sala and Tu is near, 0.033. But the distances between Sala and other four populations are far, over 0.12; Tu is close to Naxi and Shandong Han, and the distances are 0.038, 0.063 respectively; The distance between Bai and Han is the nearest, 0.007, but there is a distance, 0.075, between Bai and Naxi, and a far distance, 0.112, between Bai and Tu; The distance between Naxi and Han is 0.100 and the distances between She and other 5 populations are all over 0.12. In both of the NJ and UPGMA phylogenetic trees, Naxi, Tu and Sala is one cluster and Bai and Han is another cluster. She is a single branch. These results, basically consistent with 6 Chinese populations' geographic distribution and histories, can provide some genetic information to comprehensively study their origin, migration, formation and development with their historical records and archaeological evidence.

Genetic relationship of populations in China

Despite the fact that the continuity of morphology of fossil specimens of modern humans found in China has repeatedly challenged the Out-of-Africa hypothesis, Chinese populations are underrepresented in genetic studies. Genetic profiles of 28 populations sampled in China supported the distinction between southern and northern populations, while the latter are biphyletic. Linguistic boundaries are often transgressed across language families studied, reflecting substantial gene flow between populations. Nevertheless, genetic evidence does not support an independent origin of Homo sapiens in China. The phylogeny also suggested that it is more likely that ancestors of the populations currently residing in East Asia entered from Southeast Asia.