No CAG repeat expansion of polymerase gamma is associated with male infertility in Tamil Nadu, South India

Mitochondria contains a single deoxyribonucleic acid (DNA) polymerase, polymerase gamma (POLG) mapped to long arm of chromosome 15 (15q25), responsible for replication and repair of mitochondrial DNA. Exon 1 of the human POLG contains CAG trinucleotide repeat, which codes for polyglutamate. Ten copies of CAG repeat were found to be uniformly high (0.88) in different ethnic groups 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. Recent data suggested the implication of POLG CAG repeat expansion in infertility, but are debated. The aim of our study was to explore whether the not -10/not -10 variant is associated with spermatogenic failure. As few study on Indian population have been conducted so far to support this view, we investigated the distribution of the POLG CAG repeats in 61 infertile men and 60 normozoospermic control Indian men of Tamil Nadu, from the same ethnic background. This analysis interestingly revealed that the homozygous wild type genotype (10/-10) was common in infertile men (77% - 47/61) and in normozoospermic control men (71.7% - 43/60). Our study failed to confirm any influence of the POLG gene polymorphism on the efficiency of the spermatogenesis.