| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Gene Polymorphisms, Are Associated with the Onset of Menarche in Healthy Postmenopausal Japanese Women
Department of Obstetrics and Gynecology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan
Address all correspondence and requests for reprints to: Dr. Itsuo Gorai, Department of Obstetrics and Gynecology, International University of Health and Welfare, Atami Hospital, 13-1 Higashi-Kaigancho, Atami 413-0012, Japan. E-mail: I.gorai{at}iuhw.ac.jp.
 |
Abstract |
|---|
 Top Abstract IntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
and estrogen-metabolizing enzyme genes. Three hundred seventeen postmenopausal Japanese women, aged 46 yr and over, were enrolled in this study under informed consent. Genomic DNA was extracted from peripheral leukocytes, and PCR-based restriction fragment length polymorphism assays were used to determine estrogen receptor-: PvuII, XbaI, and estrogen-metabolizing enzymes; CYP17, estrogen biosynthesis (high activity, A2/A2, CYP1A1), hydroxylation (high inducibility, vt/vt, and COMT), inactivation (low activity, L/L) genotypes. There were no significant differences in ages at menarche and natural menopause or years of menstruation among each PvuII or XbaI genotype and seven combinations of PvuII and XbaI genotypes. We found that ages at menarche in women with A1/A2 (higher activity of CYP17; 13.6 ± 1.2 yr) were significantly earlier than in those with A1/A1 (lower activity of CYP17; 14.1 ± 1.3 yr). There were no significant differences in age at natural menopause and years of menstruation among each CYP17, CYP1A1, or COMT genotype. The small sample size of each combination of estrogen-metabolizing genotypes made it impractical to evaluate the effects of the interdependency of each genotype, including extreme genotype categories such as A2/A2L/Lvt/vt vs. A1/A1H/Hwt/wt genotypes, on ages at menarche and/or natural menopause. The results suggest that the estrogen-metabolizing CYP17 genotype influences age at menarche in healthy postmenopausal Japanese women. |
Introduction |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
Recent studies have shown that estrogen-metabolizing genes are involved in the estrogen-initiating mechanism of tumorigenesis in breast cancer. It is proposed that polymorphisms in the genes involved in estrogen biosynthesis (cytochrome P450c17; CYP17), hydroxylation (cytochrome P4501A; CYP1A1), and inactivation of the reactive metabolites (catechol-O-methyltransferase; COMT) may be associated with an elevated risk of breast cancer (19, 20, 21). There are only a few reports of the association between these polymorphisms and ages at menarche, and there is no report between the polymorphisms and ages at menopause.
Studies of genetic and environmental factors influencing the onset and cessation of menstruation have been mainly performed in a Caucasian population. Recently, genetic variations of the estrogen receptor- (ER) genes have been reported to relate to the onset of natural menopause and the risk of surgical menopause in postmenopausal women living in Rotterdam, The Netherlands (22). Women with the PP genotype had a 1.1-yr earlier onset of menopause than those with the pp genotype (P < 0.02), showing an allele dose effect that corresponds to a 0.5-yr earlier onset of menopause per copy of the P allele (P < 0.02). The risk of surgical menopause was 2.4 times higher for women carrying the PP genotype, who underwent hysterectomy due to fibroids or menorrhagia, than for those with the pp genotype. In contrast, the PvuII and XbaI polymorphisms in the ER gene were not associated with the risk of uterine leiomyomas in a large population of Italian women (23).
The studies are rarely performed in a Japanese population. The incidence of surgical menopause resulting from menorrhagia and fibroids is not as high in Japanese women compared with that in a Caucasian population. In this study we aimed to identify genetic factors affecting the onset of menarche and natural menopause in healthy postmenopausal Japanese women by investigating polymorphisms of ER genes (PvuII and XbaI) and estrogen-metabolizing enzyme genes (CYP17, CYP1A1 and COMT).
|
Subjects and Methods |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
The study population consisted of 333 postmenopausal Japanese women, aged 46 yr and over, who enrolled among 1100 healthy volunteers in the previous study (24). For all subjects, a detailed medical history, including menstrual history, was obtained. Of these, 272 women were premenopausal, and 828 were postmenopausal. All of the premenopausal women had regular menstrual cycles, and all of the postmenopausal women reported regular menstrual cycles before natural menopause. Postmenopausal status was defined as no menstrual bleeding for at least 1 yr since the last menstruation. No subject had any history of endocrine or metabolic diseases or was taking any medication, including oral contraceptive pills or estrogen replacement therapy.
Of 828 postmenopausal women, 333 subjects who responded to our follow-up program of bone density measurement were recruited for genotyping of ER and the estrogen-metabolizing enzymes. Of 333 subjects, 11 subjects for whom ages at menarche were 18 yr or greater (diagnosed as primary amenorrhea) and 5 subjects for whom ages at menopause were 40 yr or earlier (diagnosed as premature ovarian failure) were excluded from the study. All gave informed consent before this study.
Genotyping
Genomic DNA was extracted from peripheral leukocytes using a QIAamp blood kit (QIAGEN, Valencia, CA). PCR-based restriction fragment length polymorphism (RFLP) assays were used to determine ER (25), CYP17 (21, 26), CYP1A1 (27), and COMT (19) genotypes of the subjects. To ensure that the observed polymorphisms were specific and were not the results of experimental variation, identical results were obtained by repeating the assay in 100 samples studied.
DNA analysis of the ER genotype was carried out using the method reported by Yaich et al. (25). The PCR product contains a part of intron 1 and exon 2 of the ER gene and was digested with PvuII or XbaI (Takara, Tokyo, Japan) (28). The RFLPs were coded as P-p (PvuII) and X-x (XbaI), with uppercase letters signifying the absence and lowercase letters the presence of the restriction site. Genotypes of the estrogen-metabolizing enzymes, CYP17, CYP1A1, and COMT, were determined by digestion with MspAI, MspI, and Hsp92II, respectively. The RFLPs of CYP17, CYP1A1, and COMT were coded as A1-A2 (MspAI), wt-vt (MspI), and H-L (Hsp92II), respectively, with A1, wt, and H showing the absence, and A2, vt, and L the presence of the restriction site (21). The gene names, the restriction enzymes used for RFLP analysis, the names of specific RFLPs, and the chromosomal location were summarized in Table 1
.
|
Data were expressed as the mean ± SD, with P value less than 0.05 accepted as the value of significance. Differences in anthropometric characteristics, age at menarche and natural menopause, and years of menstruation among the different ER and estrogen-metabolizing enzyme genotypes were tested using ANOVA, followed by Bonferroni’s test. All analyses were performed using the Statistical Analysis System (SAS Institute, Inc., Cary, NC).
|
Results |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
. The mean age at menopause was 50.2 ± 2.9 yr, which is consistent with the report of the Committee of Reproductive Endocrinology of the Japanese Society of Obstetrics and Gynecology published in 1995 that median age at menopause is 50.54 yr.
|
ER RFLPs
We first determined the associations between ER genotypes and ages at menarche and natural menopause or years of menstruation. The frequencies of ER PvuII and XbaI RFLPs allele in this study were similar to those in other reports in Japanese women (28) (Table 3). The distribution of each genotype followed Hardy-Weinberg equilibrium, which indicates that no selection has occurred among genotypes. We could not find any significant differences in ages at menarche and natural menopause, and years of menstruation among each PvuII and XbaI genotypes. Median ages at menarche and natural menopause were 14.0 and 50.0 yr in each PvuII and XbaI genotype, respectively (Table 3). We then combined the two RFLPs of ER genotypes together in all subjects and recognized seven genotypes (numbers in parentheses): PPXX (9), PPXx (20), PPxx (17), PpXx (70), Ppxx (91), ppXx (7), and ppxx (101). Two genotypes (PpXX and ppXX) were not detected in the population examined in this study. There were no significant differences in clinical characteristics of all subjects classified by the combination of ER genotypes. We could not find any significant differences in ages at onset and cessation of menstruation, and years of menstruation among seven combinations of PvuII and XbaI genotypes.
|
We next asked whether the polymorphisms of estrogen-metabolizing genes are related to the onset, cessation, and the duration of menstruation. The distribution of CYP17 (MspAI) was similar to that of other study in Japanese population (29) (Table 4). The frequencies of each genotype were observed in agreement with Hardy-Weinberg equilibrium. We found that the age at menarche in women with A1/A2 (higher activity of CYP17; 13.6 ± 1.2 yr) was significantly earlier than that in women with A1/A1 (lower activity of CYP17; 14.1 ± 1.3 yr). The age at menarche in women with A2/A2 genotype (13.9 ± 1.3 yr) was earlier than that in women with A1/A1, and the difference did not reach a significant level (Table 4). There were no significant differences in age at menarche among each CYP1A1 and COMT genotype. Each CYP17, CYP1A1, and COMT genotype did not relate to age at natural menopause and years of menstruation. The median age at menarche was 14.0 yr in each CYP17, CYP1A1, and COMP genotype. The median age at natural menopause was 50.0 yr in each CYP17 and COMP genotype, whereas it differed in CYP1A1 genotypes (51.0 yr in vt/vt genotype and 50.0 yr both in wt/vt and wt/wt genotypes; Table 4). We then tried to evaluate the interdependency of each estrogen-metabolizing genotype [low activity COMT (COMT L/L), high inducibility CYP1A1 (CYP1A1 vt/vt), and high activity CYP17 (CYP17 A2/A2)] on ages at menarche and/or natural menopause. Theoretically, there could be 32 potential combinations; however, in this study we had 27 combinations. In addition, in 17 combinations, the number of samples with each combination is less than 8 subjects. We first tried to compare the extreme genotype categories, such as A2/A2L/Lvt/vt vs. A1/A1H/Hwt/wt genotypes. Unfortunately, the number of women with A2/A2L/Lvt/vt genotypes was 1, and the number of those with A1/A1H/Hwt/wt genotypes was 18, making statistical analysis impractical between the 2 genotype combinations. It was not feasible to analyze the interdependency comparison further in this study.
|
|
Discussion |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
First, we asked whether there was an association between age at menarche or natural menopause and ER genotype in healthy postmenopausal Japanese women. The estrogen derived from the ovary not only plays a crucial role as a positive regulation of the preovulatory gonadotropin surge, but also increases its own receptor levels in granulosa cells of the growing follicles. ER is present in various regions of the hypothalamus. Estradiol (E2) induces GnRH release from the hypothalamus and increases the level of GnRH receptors in the anterior pituitary (30). The deterioration of hypothalamic ER function reduces the positive regulatory effect of E2 on the hypothalamic-pituitary axis, causing a reduction in the frequency and/or amplitude of the preovulatory gonadotropin surge and defective ovulation (31).
In this investigation we could not find any association between age at natural menopause and ER PvuII and XbaI genotypes in a healthy Japanese population. Neither were ages at menarche associated with the PvuII and XbaI gene polymorphisms. The difference between the Rotterdam study (22) and our results may be partially explained by the difference in genetic backgrounds, Caucasians vs. Asians. Moreover, the population of this study consisted solely of healthy women with natural menopause, whereas the Rotterdam study included women with both natural and surgical menopause.
Secondly, we asked whether ages at menarche and/or natural menopause relate to genotypes of estrogen-metabolizing enzymes in a Japanese population. The breast cancer risk has been shown to be associated with three genotypes of estrogen-metabolizing enzymes and to be highest for low activity COMT (COMT L/L), followed by high inducibility CYP1A1(CYP1A1 vt/vt) and high activity CYP17(CYP17 A2/A2), genotypes (21). Further, women with the A2/A2 genotype had elevated levels of estrone and E2 compared with women with the A1/A1 genotype, suggesting that the A2 allele modified endogenous hormone levels (20). We hypothesized that genotypes of CYP17, CYP1A1, and COMT; estrogen biosynthesis, hydroxylation, and inactivation, respectively, may influence ages at menarche and/or natural menopause, as cigarette smoking increases the risk of early menopause through its effects on inhibition of aromatization and increment of estrogen clearance (32). We could not find any association between age at menopause and estrogen-metabolizing genotypes. On the other hand, we did find the age at menarche in women with the A1/A2 genotype was significantly earlier than that in women with the A1/A1 genotype (Table 4
). The menarcheal age in women with the A2/A2 genotype was earlier than in those with A1/A1 genotype and the difference did not reach a significant level. These suggest that higher activity of CYP17 (A2 allele) may contribute to the earlier onset of menstruation in Japanese population. Interestingly, median age at menarche did not differ among each CYP17 genotype. Among control subjects in the studies of breast cancer, the mean age of menarche in women carrying A1/A1 was statistically significantly higher than that in women carrying the A2 allele (13.4 vs. 13.0 yr; P = 0.047) in one study (26), whereas the median age at menarche did not differ significantly by genotype (A1/A1, 13.0 yr; A1/A2+A2/A2, 12.0 yr; P = 0.97) in another study (20). The result of this study is consistent with that of the former study, but not with the latter.
Ovarian steroids, E2 and progesterone, can modulate the release of pituitary gonadotropins by negative and positive feedback effects exerted at the level of the anterior pituitary and hypothalamus (33), indicating that estrogen-metabolizing enzymes may influence the timing of menarche. The higher activity of CYP17 (A2 allele), the lower activity of COMT (L allele), and the higher inducibility of CYP1A1 (vt allele) may influence earlier ages at menarche, as the ages at menarche in women with A1/A2 genotype were significantly earlier than in those with A1/A1 genotype. We could not analyze the interdependency of each estrogen-metabolizing genotype, including extreme genotype categories such as A2/A2L/Lvt/vt vs. A1/A1H/Hwt/wt, on ages at menarche and/or natural menopause, because of the small sample sizes of women with these genotypes. The interrelationships between combinations of each estrogen-metabolizing genotype and ages at menarche and/or natural menopause remain to be elucidated in future studies until a larger sample size is obtained, and a comparison of the extreme genotype categories is performed.
This study has several limitations. First, there may have been bias due to incorrectness in self-report of the ages at menarche and/or menopause. However, this bias does not seem to differ between each ER and estrogen-metabolizing genotypes. We could not find any difference in the number of answered questions between the groups. Second, our subjects were community dwelling, and therefore our results may not apply to other populations in Japan. Nevertheless, the distributions of ER PvuII, XbaI, and estrogen hydroxylation CYP17 were similar to those in other reports of Japanese women (28, 29), suggesting the applicability of our results to other Japanese populations. Third, the number of women in the study population is rather small for such an analysis, which makes difficult a detailed analysis of the association between minor genotypes and ages at menarche and/or menopause.
In summary, estrogen-metabolizing CYP17 (A2 allele) may influence age at menarche in healthy postmenopausal Japanese women.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
, estrogen receptor-; RFLP, restriction fragment length polymorphism. Received March 6, 2002.
Accepted November 18, 2002.
|
References |
|---|
|
TopAbstractIntroductionSubjects and MethodsResultsDiscussionReferences |
|---|
gene polymorphisms in Italian women with surgical uterine leiomyomas. Fertil Steril 75:567–570[CrossRef][Medline]
gene (CYP17) polymorphism predicts use of hormone replacement therapy. Cancer Res 59:3908–3910This article has been cited by other articles:
 |
|
 |
|
  N. Mendoza, F. J. Moron, F. Quereda, F. Vazquez, M. C. Rivero, T. Martinez-Astorquiza, L. M. Real, R. Sanchez-Borrego, A. Gonzalez-Perez, and A. Ruiz A Digenic Combination of Polymorphisms Within ESR1 and ESR2 Genes Are Associated With Age at Menarche in the Spanish Population Reproductive Sciences, March 1, 2008; 15(3): 305 - 311. [Abstract] [PDF]
|
|
|
|
 |
|
 M. E. Kevenaar, A. P.N. Themmen, F. Rivadeneira, A. G. Uitterlinden, J. S.E. Laven, N. M. van Schoor, P. Lips, H. A.P. Pols, and J. A. Visser A polymorphism in the AMH type II receptor gene is associated with age at menopause in interaction with parity Hum. Reprod., September 1, 2007; 22(9): 2382 - 2388. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Zhao, D.-H. Xiong, Y. Guo, T.-L. Yang, R. R. Recker, and H.-W. Deng Polymorphism in the insulin-like growth factor 1 gene is associated with age at menarche in caucasian females Hum. Reprod., June 1, 2007; 22(6): 1789 - 1794. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. M. Nathan, C. A. Hodges, P. J. Supelak, L. C. Burrage, J. H. Nadeau, and M. R. Palmert A Quantitative Trait Locus on Chromosome 6 Regulates the Onset of Puberty in Mice Endocrinology, November 1, 2006; 147(11): 5132 - 5138. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Guo, D.-H. Xiong, T.-L. Yang, Y.-F. Guo, R. R. Recker, and H.-W. Deng Polymorphisms of estrogen-biosynthesis genes CYP17 and CYP19 may influence age at menarche: a genetic association study in Caucasian females Hum. Mol. Genet., August 15, 2006; 15(16): 2401 - 2408. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Guo, H. Shen, P. Xiao, D.-H. Xiong, T.-L. Yang, Y.-F. Guo, J.-R. Long, R. R. Recker, and H.-W. Deng Genomewide Linkage Scan for Quantitative Trait Loci Underlying Variation in Age at Menarche J. Clin. Endocrinol. Metab., March 1, 2006; 91(3): 1009 - 1014. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J-R Long, H Xu, L-J Zhao, P-Y Liu, H Shen, Y-J Liu, D-H Xiong, P Xiao, Y-Z Liu, V Dvornyk, et al. The oestrogen receptor {alpha} gene is linked and/or associated with age of menarche in different ethnic groups J. Med. Genet., October 1, 2005; 42(10): 796 - 800. [Full Text] [PDF]
|
|
|
|
 |
|
 H. S. Kok, K. M. van Asselt, Y. T. van der Schouw, P. H.M. Peeters, and C. Wijmenga Genetic studies to identify genes underlying menopausal age Hum. Reprod. Update, September 1, 2005; 11(5): 483 - 493. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Xita, A. Tsatsoulis, I. Stavrou, and I. Georgiou Association of SHBG gene polymorphism with menarche Mol. Hum. Reprod., June 1, 2005; 11(6): 459 - 462. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. F. Masson, L. Sharp, S. C. Cotton, and J. Little Cytochrome P-450 1A1 Gene Polymorphisms and Risk of Breast Cancer: A HuGE Review Am. J. Epidemiol., May 15, 2005; 161(10): 901 - 915. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L.A. Hefler, C. Grimm, G. Heinze, C. Schneeberger, M.W. Mueller, A. Muendlein, J.C. Huber, S. Leodolter, and C.B. Tempfer Estrogen-metabolizing gene polymorphisms and age at natural menopause in Caucasian women Hum. Reprod., May 1, 2005; 20(5): 1422 - 1427. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. S. Kok, N. C. Onland-Moret, K. M. van Asselt, C. H. van Gils, Y. T. van der Schouw, D. E. Grobbee, and P. H.M. Peeters No association of estrogen receptor {alpha} and cytochrome P450c17{alpha} polymorphisms with age at menopause in a Dutch cohort Hum. Reprod., February 1, 2005; 20(2): 536 - 542. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Sharp, A. H. Cardy, S. C. Cotton, and J. Little CYP17 Gene Polymorphisms: Prevalence and Associations with Hormone Levels and Related Factors. A HuGE Review Am. J. Epidemiol., October 15, 2004; 160(8): 729 - 740. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Yamada, F. Sata, E. H. Kato, Y. Saijo, S. Kataoka, M. Morikawa, S. Shimada, T. Yamada, R. Kishi, and H. Minakami A polymorphism in the CYP17 gene and intrauterine fetal growth restriction Mol. Hum. Reprod., January 1, 2004; 10(1): 49 - 53. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A.-S. Parent, G. Teilmann, A. Juul, N. E. Skakkebaek, J. Toppari, and J.-P. Bourguignon The Timing of Normal Puberty and the Age Limits of Sexual Precocity: Variations around the World, Secular Trends, and Changes after Migration Endocr. Rev., October 1, 2003; 24(5): 668 - 693. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
