CAG-repeat variant in the polymerase γ gene and male infertility in the Chinese population: a meta-analysis

Liu, Shuyuan; Zhang, Changjun; Haiying, Peng; Yao, Yufeng; Shi, Lei; Chen, Jinbao; Lin, Keqin; Yu, Liang; Shi, Li; Huang, Xiaoqin; Sun, Hao; Chu, Jiayou

doi:10.1038/aja.2010.91

Cited by 10 publications

(6 citation statements)

References 23 publications

(51 reference statements)

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“…In concert with the previous report,[81016] this study revealed that homozygotes with 10 repeats in both alleles (10/10) were the most common and constituted 77% of all infertile subjects which was almost equivalent to the normospermic control frequency (71.7%). Rovio et al ., 1999;[7] have shown the frequent (88%) occurrence of genotype 10/10 in different ethnic group.…”

Section: Resultssupporting

confidence: 88%

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

Poongothai

2013

Indian J Hum Genet

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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.

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Section: Resultssupporting

confidence: 88%

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

Poongothai

2013

Indian J Hum Genet

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“…Jensen et al 2004 [10], reported a significantly higher frequency of non 10/non 10 genotype in normozoospermic infertile men affected by unexplained sub fertility and normal spermiograms. In concert with the previous report [6,8,15], this study revealed that homozygotes with 10 repeats in both alleles (10/10) were the most common and constituted 79 % of all infertile subjects which was almost equivalent to the normospermic control frequency (71.7 %). Rovio et al 1999 [5], have shown the frequent (88 %) occurrence of genotype 10/10 in different ethnic group.…”

Section: Resultssupporting

confidence: 61%

“…Expansion of CAG repeat in some genes is associated with various human pathologies. Implication of POLG CAG repeats in infertility is suggested by copious studies [6][7][8][9][10], but are debated [11][12][13][14][15]. As it is not clear whether the variable CAG genotype is one of the contributing factor for male infertility, an attempt was made to screen the CAG repeat motif of POLG gene exclusively in infertile men from two different districts of Tamil Nadu, South India.…”

Section: Introductionmentioning

confidence: 99%

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

Poongothai

2013

J Assist Reprod Genet

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Purpose 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. Methods 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. Results 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. Conclusion 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.

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“…Liu et al . () published a meta‐analysis about the association between POLG‐CAG‐repeat and male infertility, in which they analysed the distribution of alleles and genotypes in six provinces, and combined 150 cases and 126 controls from Hubei province and previous case–control studies to conduct a meta‐analysis. Differing from that article, we added three studies (Brusco et al .…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, some mistakes in characteristic of case–control studies of Liu et al . () were corrected (see Data S3).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2016

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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.

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CAG-repeat variant in the polymerase γ gene and male infertility in the Chinese population: a meta-analysis

Cited by 10 publications

References 23 publications

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

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

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

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

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