Mitochondrial DNA polymerase gamma gene polymorphism is not associated with male infertility

Abstract

CAG repeat length of human miotochondrial DNA Polymerase gamma (POLG) gene is polymorphic with a major allele at 10 repeats and considered as the common allele whereas the mutant alleles (not 10/not 10 CAG repeats) were found to be associated with oligospermia / oligoasthenospermia in male infertility. To explore whether CAG trinucleotide repeat expansion in exon 1 of POLG gene is associated with spermatogenic failure. One hundred twenty four infertile men (sperm count <20million/ml) and 60 normozoospermic (sperm count >20million/ml) control Indian men of Tamil Nadu, were enrolled. DNA was extracted from 10ml of peripheral blood and from semen using standard procedures. CAG repeat expansion was analyzed by polymerase chain reaction. Amplified products were quantified by 2% agarose gel electrophoresis and subjected to genescan analysis to ascertain the size of POLG-CAG alleles. This analysis interestingly revealed that the common allele 10 (10-CAG repeats) was widespread in infertile and normozoospermic control men with a frequency of 79% and 71.7% respectively. No statistical significance was found in POLG genotypic frequency distribution between infertile men and normospermic men. The present study confirmed no association between the POLG gene polymorphism and male infertility. Thus, if associated with infertility, the POLG gene polymorphism should be only considered as a minor possible contributing factor in infertile male patients with no impact on obtaining a pregnancy.