**Acknowledgements**

The authors would like to take this opportunity to extend their sincere thanks to the Ministry of Health for providing financial support for this study. We are also grateful for the technical support of the Hanoi Medical University Hospital. We thank Dr. Shkurat TP for a critical reading of the chapter.

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**Author details**

provided the original work is properly cited.

Nguyen Thi Trang\* and Vu Thi Huyen Hanoi Medical University, Hanoi, Vietnam

\*Address all correspondence to: trangnguyen@hmu.edu..vn

*Polymorphism of Xenobiotic Detoxification Genes and Male Infertility*

*DOI: http://dx.doi.org/10.5772/intechopen.79233*

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

## **Conflict of interest**

The authors declare that they have no conflict of interest.

*Polymorphism of Xenobiotic Detoxification Genes and Male Infertility DOI: http://dx.doi.org/10.5772/intechopen.79233*

*Male Reproductive Health*

development in men.

impaired male reproduction.

**7. Conclusions**

DNA fragmentation is significantly higher in infertile men [80], this study also proves that NAT2 polymorphism is involved in the process of impaired reproductive

The latest study, conducted on Vietnam males, revealed that idiopathic male infertility is associated with both the rs1799930 (OR = 3.10, 95%; CI: 1.92–5.01) and the rs1799929 (OR = 3.74, 95%; CI: 2.26–6.18) alleles. The current research also shows that GSTP1 and NAT2 have a synergetic effect—they cause the biggest risk of infertility only when both polymorphisms are present. Namely, the 481C > T rs1799929 (NAT2) and the 341C > T or 341 T > T rs1138272 (GSTP1) cause the 17-fold increase in the risk of idiopathic male infertility (OR = 17.24, 95%; CI: 7.30–40.74, P = 0.0001) [55]. Thereby, the NAT2 involvement in the process of male infertility development is highly probable, but more data are needed to confirm its role in mediating the

Male infertility is a worldwide health problem with multifactorial etiology, show-

The authors would like to take this opportunity to extend their sincere thanks to the Ministry of Health for providing financial support for this study. We are also grateful for the technical support of the Hanoi Medical University Hospital. We

thank Dr. Shkurat TP for a critical reading of the chapter.

The authors declare that they have no conflict of interest.

ing an upward trend during the last decade. One of the most significant reasons behind this trend is the exposure to environmental factors—xenobiotics, hypo/ hyperthermia, stress or harmful radiations (such as X-rays). All this phenomena may lead to oxidative stress, treated as one of the most common trigger of male infertility and found in nearly half of all the infertile men [81]. It causes impairment of sperm maturation, testis injury, sperm motility reduction and DNA damages. Research on the polymorphisms of xenobiotic detoxification genes may be helpful for determining the interethnic and interindividual peculiarities of noxious chemicals metabolism (including possible risks of male infertility development) based on gene-environment interactions. Overall, knowledge about the SNPs of xenobiotic metabolizing genes associated with male infertility is rather inconsistent or even contradictory. Thus, more comprehensive analysis is required that would be stratified according to the age, body mass index, ethnic background, diet, smoking and drinking status, environmental exposures and other lifestyle factors. Moreover, many studies were carried out on small samples. This factor increases the probability of overestimating the association. Numerous studies indicated that such polymorphisms as CYP1A1, GSTM1, GSTT1, GSTP1 and NAT2 are most likely to be involved in male infertility development. Their polymorphic transcripts were shown to change the xenobiotic metabolism. In some cases, they failed to provide sufficient antioxidant defense. Knowledge of the role that the polymorphisms of xenobiotic detoxification genes have in male infertility development could be useful for providing sufficient diagnostic methods, as well as for providing reliable recommendations for infertile men on disease prevention and treatment.

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**Acknowledgements**

**Conflict of interest**
