Associations between androgen receptor CAG & GGN repeat polymorphism & recurrent spontaneous abortions in Chinese women
Zhang Chuan1, Dang Jie2, Xu Hao3, Bao Junhua4, Guo Mengjing5, Pei Liguo5, Yan Yousheng1, Lu Hong2, Huo Zhenghao2
1 Key Laboratory of Fertility Preservation & Maintenance, Ministry of Education, Key Laboratory of Reproduction & Heredity of Ningxia Hui Autonomous Region, Ningxia Medical University, Yinchuan, Ningxia; Gansu Provincial Maternity Child-Care Hospital, Gansu Province Medical Genetics Center, Lanzhou Gansu, PR China
2 Key Laboratory of Fertility Preservation & Maintenance, Ministry of Education, Key Laboratory of Reproduction & Heredity of Ningxia Hui Autonomous Region; Department of Medical Genetics & Cell Biology, Ningxia Medical University, Yinchuan, Ningxia, PR China
3 School of Stomatology, Fourth Military Medical University, Xi'an, PR China
4 Yinchuan Maternal Child Health Care Hospital, Yinchuan, Ningxia, PR China
5 Key Laboratory of Fertility Preservation & Maintenance, Ministry of Education, Key Laboratory of Reproduction & Heredity of Ningxia Hui Autonomous Region, Ningxia Medical University, Yinchuan, Ningxia, PR China
Dr Huo Zhenghao
Department of Medical Genetics & Cell Biology, Ningxia Medical University, 1160 Shengli Street, Yinchuan, Ningxia
Source of Support: None, Conflict of Interest: None
Background & objectives: Recurrent spontaneous abortion (RSA) is a reproductive problem that occurs in women in reproductive age with a frequency of 1-3 per cent. Previous studies have reported high levels of serum androgens to be associated with RSAs. At the molecular level, the effect of androgens is mediated through the activation of the androgen receptor (AR). The CAG and GGN repeat polymorphisms of the AR gene are associated with the AR activity. We hypothesize that the AR CAG/GGN repeat polymorphism may be associated with levels of serum androgens. Thus, this study as undertaken to evaluate the relationship between CAG/GGN repeats in exon 1 of the AR gene in women with RSAs.
Methods: This case-control study was performed in Ningxia, PR China, including 149 women with RSAs and 210 controls. The CAG and GGN repeats of the AR gene were genotyped using a PCR-based assay and were analyzed using Peak Scanner Software v1.0 to determine the CAG/GGN repeat length.
Results: CAG repeats ranged from 15 to 29 in the RSA patients, compared to 14 to 35 in the control group. The median value of CAG repeats was 22 for the RSA group and 24 for control group. The total AR CAG alleles (≤22 repeats), shorter AR CAG alleles (≤22 repeats), and biallelic means (≤22.5 repeats) were significantly different in the RSA group in comparison to the control group ( P <0.001, P <0.01). The median value of the GGN repeats was 23 for the cases and 22 for controls. The total number of AR GGN alleles (≤23 repeats) was significantly different in the RSA group compared to the control group ( P <0.5). There was no difference between the RSA group and the control groups in regards to shorter alleles, longer alleles, and biallelic means.
Interpretation & conclusions: Our observation suggests that the CAG and GGN repeat length is shorter in women with RSAs as compared with controls and that shorter CAG and GGN repeats may be pathogenic for RSAs in Chinese women. Further studies need to be done in different ethnic populations.