title: CAG-repeat variant in the polymerase γ gene and male infertility in the Chinese population: a meta-analysis.
abstract: 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.
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming 650118, China.
authors.forename: Shu-Yuan
authors.initials: SY
authors.lastname: Liu
authors.forename: Chang-Jun
authors.initials: CJ
authors.lastname: Zhang
authors.forename: Hai-Ying
authors.initials: HY
authors.lastname: Peng
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Yao
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Jin-Bao
authors.initials: JB
authors.lastname: Chen
authors.forename: Ke-Qin
authors.initials: KQ
authors.lastname: Lin
authors.forename: Liang
authors.initials: L
authors.lastname: Yu
authors.forename: Li
authors.initials: L
authors.lastname: Shi
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Huang
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.forename: Jia-You
authors.initials: JY
authors.lastname: Chu
mesh_terms: D000483:Alleles; D044466:Asian People / Q000235:genetics*; D016022:Case-Control Studies; D002681:China; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D005787:Gene Frequency; D005799:Genes, Dominant; D005808:Genes, Recessive; D014644:Genetic Variation; D006801:Humans; D007248:Infertility, Male / Q000201:enzymology* / Q000235:genetics*; D008297:Male; D018598:Minisatellite Repeats; D008957:Models, Genetic; D012307:Risk Factors; D018911:Trinucleotide Repeats
chemical_list: D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase; C413027:POLG protein, human