Endothelial nitric oxide synthase gene Glu298Asp polymorphism is associated with advanced stage endometriosis

Human Reproduction, Vol.24, No.10 pp. 2656–2659, 2009 Advanced Access publication on June 16, 2009 doi:10.1093/humrep/dep212 ORIGINAL ARTICLE Reproductive genetics Endothelial nitric oxide synthase gene Glu298Asp polymorphism is associated with advanced stage endometriosis Hoon Kim 1, Seung Yup Ku 1,2, Sung Hoon Kim 3, Gyoung Hoon Lee 4, Young Min Choi 1,2,6, Jong Mee Kim 1, Taek Hoo Lee 5, and Shin Yong Moon 1,2 1 Department of Obstetrics and Gynecology, Seoul National University College of Medicine, 28 Yungun-dong, Chongno-ku, Seoul 110 – 744, South Korea 2The Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University College of Medicine, Seoul, South Korea 3Department of Obstetrics and Gynecology, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, South Korea 4Department of Obstetrics and Gynecology, Gachon University of Medicine and Science, Incheon, South Korea 5 Department of Obstetrics and Gynecology, Kyungpook University College of Medicine, Taegu, South Korea 6 Correspondence address. Fax: þ82-2-762-3599; E-mail: background: Altered expression of endothelial nitric oxide synthase (eNOS) has been reported to be involved in the development of endometriosis. The genotypes of eNOS gene (NOS3) may be responsible for variation in its enzymatic activity as well as plasma concentration of nitric oxide. The Glu298Asp polymorphism of the NOS3 may modulate angiogenesis and influence individual susceptibility to endometriosis. This study was designed to evaluate the association between the Glu298Asp polymorphism of the NOS3 and advanced stage endometriosis. methods: This study consisted of 299 women with advanced stage endometriosis and 459 control women without endometriosis in a Korean population. Genotyping results of the Glu298Asp polymorphism of the NOS3 were analyzed between the endometriosis and control group. results: The genotypic frequencies were significantly different between women with and without endometriosis. The frequency of the non-GG genotype (GT þ TT) was higher in the endometriosis group than in the control group (P ¼ 0.001). conclusion: These findings suggest that the T allele, encoding aspartic acid, of the Glu298Asp polymorphism of the NOS3 may be associated with advanced stage endometriosis in the Korean population. Key words: endometriosis / polymorphism / eNOS / NOS3 Introduction Endometriosis, characterized by the presence and growth of ectopic endometrial tissue outside the endometrial cavity, can cause infertility, pelvic pain and dysmenorrhea. The estimated prevalence of endometriosis among women of reproductive age is as high as 18% and affects 5–50% of all infertile women (Missmer and Cramer, 2003). Although it is widely accepted that retrograde menstruation into the peritoneal cavity can lead to the development of the endometriosis, the definite etiology and pathogenesis of endometriosis remains unclear. It remains to be determined why the disease develops in only a certain group of women although retrograde menstruation occurs in most women. Endometriosis has shown heritable tendencies with recurrence risks of 5–7% for first-degree relatives, and familial and epidemiologic studies suggest polygenic and multifactorial inheritance (Bischoff and Simpson, 2004). Recently, we demonstrated that the vascular endothelial growth factor (VEGF) þ405 C/G polymorphism may be associated with the risk of advanced stage endometriosis in the Korean population (Kim et al., 2005), in addition to many other genes. Nitric oxide (NO), which is converted from L-arginine and molecular oxygen by a family of NO synthases (NOSs) (Moncada and Higgs, 1993), is known to play important roles in physiologic and pathologic pathways of almost every biological system. The three tissue-specific subtypes of this enzyme, neuronal (n), endothelial (e) and induced (i) NOS, are responsible for NO biosynthesis in various tissues (Moncada and Higgs, 1993). These not only induce cellular injury, altered vascular resistance and signal transduction (Knowles and Moncada, 1994; Duda et al., 2004) but also affect many angiogenic & The Author 2009. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: 2657 eNOS gene polymorphism in endometriosis factors (Duda et al., 2004). In a mouse model, the endothelial nitric oxide synthase (eNOS) mediates VEGF-induced vascular permeability, vessel tone and angiogenesis (Fukumura et al., 2001). Thus, eNOS may play a role in the development of endometriosis via angiogenetic enhancement since angiogenesis is essential for the survival of ectopic endometrial tissue outside the uterus as well as the progression of endometriosis (Donnez et al., 1998). In endometrial cells, NO is synthesized by eNOS (Marsden et al., 1993) and the expression of eNOS in endometrium has been shown to be phase-dependent changes during normal menstrual cycles (Ota et al., 1998). The expression of eNOS in endometrium is increased throughout the menstrual cycle in patients with endometriosis compared with women without endometriosis (Ota et al., 1998), and higher levels of NO were found in ectopic endometrium compared with eutopic endometrium (Wu et al., 2003). Furthermore, Khorram and Lessey (2002) demonstrated that the expression of eNOS is significantly increased in the glandular and luminal epithelium in patients with endometriosis. Taken together, the roles for eNOS have been implicated in the development of endometriosis. The eNOS gene (NOS3) has numerous polymorphisms including a variable-number tandem repeats in intron 4, the T-786C polymorphism in the promoter region, and the Glu298Asp (G894T, rs1799983) polymorphism in exon 7. Among these reported polymorphisms of the NOS3, the Glu298Asp polymorphism leads to an amino acid substitution in the mature protein (Casas et al., 2006; http:// pga.gs.washington.edu) that may cause a change in its enzymatic activity. With regard to the association between the NOS3 Glu298Asp polymorphism and endometriosis, there are only two reports with conflicting results in Greek and Indian women (Zervou et al., 2003; Bhanoori et al., 2008). Therefore, it is necessary to evaluate whether the NOS3 Glu298Asp polymorphism is associated with the risk of endometriosis in other ethnic groups including larger number of samples. For this purpose, we sought to investigate the association of the NOS3 Glu298Asp polymorphism with the risk of advanced stage endometriosis in the Korean population. or ovarian cancer were excluded from the control group. The indications for surgery or diagnostic laparoscopy among the control group were benign ovarian cyst, pelvic pain or dysmenorrhea, tubal ligation, carcinoma in situ of the uterine cervix and tubal reanastomosis. Subject ages ranged from 19 to 44 years (29.7 + 5.3, mean + SD) in the endometriosis group and from 19 to 55 years (41. (...truncated)