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

Asian J Androl. 2011 Mar;13(2):298-304. doi: 10.1038/aja.2010.91. Epub 2010 Nov 22.

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.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Asian People / genetics*
  • Case-Control Studies
  • China
  • DNA Polymerase gamma
  • DNA-Directed DNA Polymerase / genetics*
  • Gene Frequency
  • Genes, Dominant
  • Genes, Recessive
  • Genetic Variation
  • Humans
  • Infertility, Male / enzymology*
  • Infertility, Male / genetics*
  • Male
  • Minisatellite Repeats*
  • Models, Genetic
  • Risk Factors
  • Trinucleotide Repeats*

Substances

  • DNA Polymerase gamma
  • DNA-Directed DNA Polymerase
  • POLG protein, human