Biotechnology Department, PSG College of Technology, Coimbatore, 641004, Tamil Nadu, India,
J Assist Reprod Genet. 2013 Sep;30(9):1109-14. doi: 10.1007/s10815-013-0058-2. Epub 2013 Aug 4.
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 <20 million/ml) and 60 normozoospermic (sperm count >20 million/ml) control Indian men of Tamil Nadu, were enrolled. DNA was extracted from 10 ml 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.
人类线粒体 DNA 聚合酶γ（POLG）基因的 CAG 重复长度具有多态性，主要等位基因重复 10 次，被认为是常见等位基因，而突变等位基因（非 10/非 10 CAG 重复）与男性不育症的少精症/弱精症有关。探讨 POLG 基因外显子 1 中的 CAG 三核苷酸重复扩展是否与精子发生失败有关。
我们招募了 124 名不育男性（精子计数<2000 万/ml）和 60 名正常生育男性（精子计数>2000 万/ml）作为对照组，这些男性均来自印度泰米尔纳德邦。采用标准程序从外周血和精液中提取 DNA。通过聚合酶链反应分析 CAG 重复扩展。通过 2%琼脂糖凝胶电泳对扩增产物进行定量，并进行基因扫描分析，以确定 POLG-CAG 等位基因的大小。
有趣的是，这项分析表明，常见等位基因 10（10-CAG 重复）在不育和正常生育对照组男性中广泛存在，其频率分别为 79%和 71.7%。不育男性和正常生育男性之间 POLG 基因型频率分布无统计学意义。
本研究证实 POLG 基因多态性与男性不育之间无关联。因此，如果与不育有关，POLG 基因多态性应仅被视为不育男性患者中可能的次要因素，对获得妊娠无影响。
