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 y （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 IO-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 （0R）=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 lO/not 10 versus 10110： OR= 1.34; 95% Ch 0.66-2.72）, heterozygote comparison （lO/not 10 versus 10/10： OR= 1.04; 95% Ch 0.78-1.38）, dominant model comparison （not lO/not 10＋ 101 not 10 versus 10110. OR= 1.08; 95% Ch 0.79-1.47） and recessive genetic comparison （not lO/not 10 versus lO/not 10＋ 10/10- OR= 1.31; 95% Ch 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.

HLA polymorphism of the Zhuang population reflects the common HLA characteristics among Zhuang-Dong language-speaking populations

A study of the human leukocyte antigen （HLA） genetic characteristics in the Zhuang, the largest ethnic population in China, would provide insight into Zhuang history and give a useful tool for disease associations, transplantation, and anthropology. In the present study, we report the comprehensive HLA-A, HLA-B, HLA-C, and HLA-DRB1 alleles and haplotypes in the Zhuang population of southern China for the first time. A total of 13 HLA-A, 24 HLA-B, 22 HLA-C, and 18 HLA-DRB1 were identified in 104 Zhuang individuals. The frequencies of HLA-A＊11：01, A^＊02：07, A^＊24：02, A^＊02：03, and A^＊33：03 on A loci, B^＊15：02, B^＊58：01, B^＊46：01, and B^＊13：01 on B loci, C^＊03：04, C^＊08：01, C^＊01：02, C^＊03：02, and C^＊07：02 on C loci, and DRBl＊15：01, DRBl^＊16：02, DRB1^＊14：01, DRBl^＊15：02, and DRBI^＊03：01 on the DRB1 loci were 〉10%. The A^＊33：03-C^＊03：02-B^＊58：01-DRBl^＊03：01 and A^＊02：07-C^＊01：02- B^＊46：01-DRB1^＊14：01 haplotypes were predominant in the Zhuang. The phylogenetic tree, as well as the analysis of haplotypes, suggested that the Zhuang are genetically similar to southern Chinese populations, especially the Zhuang-Dong language-speaking populations, such as the Bouyei, Dai, and Maonan. Even though the Zhuang and southern Chinese populations shared common alleles and haplotypes, the Zhuang has maintained its unique genetic characteristics.

Strong association of SLCIA1 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 SLCIA1 （P = 1.919E-4, OR = 0.5905, 95% Ch 0.447-0.78） and rs10129954 in DPF3 （P = 0.0023, OR = 2.199, 95% Ch 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 PEXIO （P= 0.0011, OR = 2.935, 95% Ch 1.492-5.775）. In addition, six SNPs （rs215702 in LSMS, rs6476866 in SLCIA1, rs10129954 in DPF3, rs1801133 in MTHFR, rs2477686 in PEXIO, 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.

Positive Selection of CAG Repeats of the ATXN2 Gene in Chinese Ethnic Groups

The ataxin-2 （ATXN2） gene is located on human chromo-some 12q24.1. In normal individuals, the coding region in exon 1 of this gene has fewer than 31 CAG repeats （Yu et al., 2005： Laffita-Mesa et al., 2012）. However, an abnormal expansion of CAG trinucleotide repeats results in the aggre-gation of polyglutamine （polyQ）, which causes spinocer-ebellar ataxia type 2 （SCA2） （Pulst et al., 1996）. The expanded alleles have more than 32 repeats in the affected individuals, and generally there is an inverse correlation between CAG repeat length and age of onset （Pulst et al., 1996）. SCA2 is an autosomal dominant inheritance neurodegenerative disease, whose major clinical feature is progressive cerebellar ataxia. Atrophies of the brainstem and frontal lobe have been frequently detected by magnetic resonance imaging （MRI） （Yamamoto-Watanabe et al., 2010）. This disease has the strong effect on sensory and motor control.