CAG-repeat polymorphisms in the polymerase γ gene and male infertility: a meta-analysis

CAG-repeat in the polymerase γ (POLG) gene encoding polymerase γ for mitochondria is important to spermatogenesis. Compared with a few researchers who raised alteration of CAG-repeat-affected male reproductive ability, others did not find the association between CAG-repeat polymorphisms and male infertility. Therefore, a comprehensive meta-analysis is necessary to determine the association; 13 case-control studies were screened out using keywords search. From these studies, characteristics were extracted for conducting meta-analysis. Odds ratio (OR) and 95% confidence interval (CI) were used to describe the results; the results indicated that CAG-repeat allele was not a risk factor to male infertility (pooled OR = 1.03, 95% CI: 0.79-1.34, P = 0.828). Four different genetic comparisons also demonstrated a negative result: heterozygote comparison (not 10/10 versus 10/10. Pooled OR = 0.99, 95% CI: 0.77-1.27, P = 0.948), homozygote comparison (not 10/not 10 versus 10/10. Pooled OR = 1.08, 95% CI: 0.56-2.06, P = 0.816), the recessive genetic comparison (not 10/not 10 versus not 10/10 + 10/10. Pooled OR = 1.07, 95% CI: 0.58-1.95, P = 0.829) and the dominant genetic comparison (not 10/not 10 + not 10/10 versus 10/10. Pooled OR = 0.97, 95% CI: 0.72-1.29, P = 0.804); based on current researches, this meta-analysis demonstrated no apparent association between POLG-CAG-repeat and male infertility. Similarly, CAG-repeat was not a sensitive site to male infertility.