Harris T P, Gomas K P, Weir F, Holyoake A J, McHugh P, Wu M, Sin Y, Sin I L, Sin F Y T
School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
Int J Androl. 2006 Jun;29(3):421-33. doi: 10.1111/j.1365-2605.2005.00633.x. Epub 2006 Feb 20.
CAG trinucleotide repeat length in the nuclear polymerase gamma gene (POLgamma) has been shown to be associated with men with reduced fertility. The present study investigated the frequency of CAG repeat length genotypes and three exonuclease motifs of the POLgamma in relation to the frequency of mitochondrial nucleotide substitutions. DNA from semen samples of 93 normozoospermic men and 192 non-normozoospermic men was isolated and the specific regions of the genes were amplified by polymerase chain reactions (PCR) and sequenced to identify mutations. The genotypic frequencies of pooled POLgamma CAG repeat lengths, =10/ not equal 10 heterozygotes and not equal 10/ not equal 10 homozygotes, were significantly different between normozoospermic and non-normozoospermic men (p < 0.05), with non-normozoospermic men having a slightly higher frequency of the =10/=10 genotypes. The allelic frequency for =10 is 0.79 and not equal10 is 0.21 for normozoospermic men and 0.85 and 0.15, respectively, for non-normozoospermic men (p < 0.025). There was no mutation detected in the exonuclease motifs in all the samples tested. Eighty normozoospermic and 124 non-normozoospermic semen samples were analysed for nucleotide substitutions in mitochondrial genes by PCR and sequencing. Heteroplasmic mutations were found in one azoospermic man, four asthenozoospermic men and two normozoospermic men. Only one asthenozoospermic man was heterozygous for the POLgamma genotype. Of the 17 men with non-synonymous nucleotide substitutions, 14 were homozygous for the POLgamma genotype. Non-normozoospermic men had twice as many nucleotide substitutions than normozoospermic men. However, there were no significant differences in the frequencies of nucleotide substitution and POLgamma genotypes in the two groups of men.
已证明核聚合酶γ基因（POLgamma）中的CAG三核苷酸重复长度与生育力降低的男性有关。本研究调查了POLgamma的CAG重复长度基因型频率和三个核酸外切酶基序与线粒体核苷酸替换频率的关系。从93名正常精子男性和192名非正常精子男性的精液样本中分离DNA，通过聚合酶链反应（PCR）扩增基因的特定区域并进行测序以鉴定突变。正常精子和非正常精子男性中，POLgamma CAG重复长度的合并基因型频率（=10/不等于10杂合子和不等于10/不等于10纯合子）存在显著差异（p<0.05），非正常精子男性中=10/=10基因型的频率略高。正常精子男性中=10的等位基因频率为0.79，不等于10的为0.21；非正常精子男性中分别为0.85和0.15（p<0.025）。在所有测试样本的核酸外切酶基序中均未检测到突变。通过PCR和测序分析了80份正常精子和124份非正常精子精液样本中线粒体基因的核苷酸替换情况。在1名无精子症男性、4名弱精子症男性和2名正常精子男性中发现了异质性突变。只有1名弱精子症男性的POLgamma基因型为杂合子。在17名具有非同义核苷酸替换的男性中，14名的POLgamma基因型为纯合子。非正常精子男性的核苷酸替换数量是正常精子男性的两倍。然而，两组男性中核苷酸替换频率和POLgamma基因型频率没有显著差异。
