Lack of association between endometriosis and the CYP17 MspA1 polymorphism in UK and Japanese populations

Polymorphisms and endometriosis: a systematic review and meta-analyses

BACKGROUND

Endometriosis is an estrogen-dependent gynecological disorder that affects at least 10% of women of reproductive age. It may lead to infertility and non-specific symptoms such as chronic pelvic pain. Endometriosis screening and diagnosis are difficult and time-consuming. Late diagnosis (with a delay ranging from 3.3 to 10.7 years) is a major problem and may contribute to disease progression and a worse response to treatment once initiated. Efficient screening tests might reduce this diagnostic delay. As endometriosis is presumed to be a complex disease with several genetic and non-genetic pathogenic factors, many researchers have sought to identify polymorphisms that predispose to this condition.

OBJECTIVE AND RATIONALE

We performed a systematic review and meta-analysis of the most regularly reported polymorphisms in order to identify those that might predispose to endometriosis and might thus be of value in screening.

SEARCH METHODS

The MEDLINE database was searched for English-language publications on DNA polymorphisms in endometriosis, with no date restriction. The PubTator text mining tool was used to extract gene names from the selected publications' abstracts. We only selected polymorphisms reported by at least three studies, having applied strict inclusion and exclusion criteria to their control populations. No stratification based on ethnicity was performed. All steps were carried out according to PRISMA guidelines.

OUTCOMES

The initial selection of 395 publications cited 242 different genes. Sixty-two genes (corresponding to 265 different polymorphisms) were cited at least in three publications. After the application of our other selection criteria (an original case-control study of endometriosis, a reported association between endometriosis and at least one polymorphism, data on women of reproductive age and a diagnosis of endometriosis in the cases established by surgery and/or MRI and confirmed by histology), 28 polymorphisms were eligible for meta-analysis. Only five of the 28 polymorphisms were found to be significantly associated with endometriosis: interferon gamma (IFNG) (CA) repeat, glutathione S-transferase mu 1 (GSTM1) null genotype, glutathione S-transferase pi 1 (GSTP1) rs1695 and wingless-type MMTV integration site family member 4 (WNT4) rs16826658 and rs2235529. Six others showed a significant trend towards an association: progesterone receptor (PGR) PROGINS, interCellular adhesion molecule 1 (ICAM1) rs1799969, aryl-hydrocarbon receptor repressor (AHRR) rs2292596, cytochrome family 17 subfamily A polypeptide 1 (CYP17A1) rs743572, CYP2C19 rs4244285 and peroxisome proliferator-activated receptor gamma (PPARG) rs1801282), and 12 showed a significant trend towards the lack of an association: tumor necrosis factor (TNF) rs1799964, interleukin 6 (IL6) rs1800796, transforming growth factor beta 1 (TGFB1) rs1800469, estrogen receptor 1 (ESR1) rs2234693, PGR rs10895068, FSH receptor (FSHR) rs6166, ICAM1 rs5498, CYP1A1 rs4646903, CYP19A1 rs10046, tumor protein 53 (TP53) rs1042522, X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1) rs25487 and serpin peptidase inhibitor clade E member 1 (SERPINE1) rs1799889; however, for the 18 polymorphisms identified in the latter two groups, further studies of the potential association with the endometriosis risk are needed. The remaining five of the 28 polymorphisms were not associated with endometriosis: glutathione S-transferase theta 1 (GSTT1) null genotype, vascular endothelial growth factor alpha (VEGFA) rs699947, rs833061, rs2010963 and rs3025039.

WIDER IMPLICATIONS

By carefully taking account of how the control populations were defined, we identified polymorphisms that might be candidates for use in endometriosis screening and polymorphisms not associated with endometriosis. This might constitute the first step towards identifying polymorphism combinations that predispose to endometriosis (IFNG (CA) repeat, GSTM1 null genotype, GSTP1 rs1695, WNT4 rs16826658 and WNT4 rs2235529) in a large cohort of patients with well-defined inclusion criteria. In turn, these results might improve the diagnosis of endometriosis in primary care. Lastly, our present findings may enable a better understanding of endometriosis and improve the management of patients with this disease.

Association study between CYP17 gene polymorphism and endometriosis risk: a meta-analysis

The cytochrome P450 subfamily 17 (CYP17) gene T > C polymorphism is associated with endometriosis risk. However, studies on the association between the genotyping of MspA1 polymorphism in the 5'-untranslated region of the CYP17 gene and endometriosis risk have reported controversial results. The aim of the present study was to obtain a more precise estimate of the relationship of CYP17 gene polymorphism with endometriosis risk. Relevant articles published up to April 2014 were obtained from Pubmed, Embase, and Cochrane Central electronic databases. Case-control studies about the association between CYP17 gene polymorphisms and endometriosis were selected. Eligible data were extracted by two independent reviewers. The strength of the association between CYP17 and endometriosis was assessed by pooled odds ratios (OR) with 95% confidence intervals (CI). Eligible case-control studies involving 1000 cases and 1167 controls were analyzed from 280 studies. The pooled results showed no association between the CYP17 gene T > C polymorphism and endometriosis risk in the overall population (CC vs TT: OR = 0.92, 95% CI = 0.52-1.61, P = 0.762; TC vs TT: OR = 1.01, 95% CI = 0.72-1.42, P = 0.949; dominant model: OR = 0.94, 95% CI = 0.64-1.39, P = 0.763; recessive model: OR = 0.93, 95% CI = 0.64-1.35, P = 0.712). In the subgroup analysis based on ethnicity, no significant association was found in Asians, Caucasians and mixed population under a recessive model (Asians: OR = 0.76, 95% CI = 0.53-1.07, P = 0.118; Caucasians: OR = 2.47, 95% CI = 0.45-13.66, P = 0.300; mixed population: OR = 1.40, 95% CI = 0.65-3.02, P = 0.712). In conclusion, the meta-analysis suggested that the CYP17 gene polymorphism was not associated with endometriosis risk. Considering the limited sample size and ethnicity included in our meta-analysis, an updated meta-analysis needs to be conducted when larger and more well-designed studies are published.

Risk for estrogen-dependent diseases in relation to phthalate exposure and polymorphisms of CYP17A1 and estrogen receptor genes

Evidence has shown that polymorphisms of various genes known to be involved in estrogen biosynthesis and function are associated with estrogen-dependent diseases (EDDs). These genes include CYP17A1, estrogen receptor 1 (ESR1), and 2 (ESR2). Phthalates are considered estrogenic endocrine disruptors, and recent research has suggested that they may act as a risk factor for EDDs. However, extremely few studies have assessed the effects of gene-environment interaction on these diseases. We recruited 44 patients with endometriosis or adenomyosis, 36 patients with leiomyoma, and 69 healthy controls from a medical center in Taiwan between 2005 and 2007. Urine samples were collected and analyzed for seven phthalate metabolites using liquid chromatography tandem mass spectrometry. Peripheral lymphocytes were used for DNA extraction to determine the genotype of CYP17A1, ESR1, and ESR2. Compared to controls, patients with leiomyoma had significantly higher levels of total urinary mono-ethylhexyl phthalate (ΣMEHP) (52.1 vs. 29.6 μg/g creatinine, p = 0.040), mono-n-butyl phthalate (MnBP) (75.4 vs. 51.3 μg/g creatinine, p = 0.019), and monoethyl phthalate (MEP) (103.7 vs. 59.3 μg/g creatinine, p = 0.031). In contrast, patients with endometriosis or adenomyosis showed a marginally increased level of urinary MEHP only. Subjects who were homozygous for both the ESR1 C allele (rs2234693) and CYP17A1 C allele (rs743572) showed a significantly increased risk for leiomyoma (OR = 19.8; 95 % CI, 1.70; 231.5; p = 0.017) relative to subjects with other genotypes of ESR1 and CYP17A1. These results were obtained after adjusting for age, cigarette smoking, MEHP level, GSTM1 genotype and other covariates. Our results suggested that both CYP17A1 and ESR1 polymorphisms may modulate the effects of phthalate exposure on the development of leiomyoma.

Screening of a panel of steroid-related genes showed polymorphisms of aromatase genes confer susceptibility to advanced stage endometriosis in the Taiwanese Han population

OBJECTIVE

To establish a multilocus model for studying the effect of steroid-related genes on advanced stage endometriosis.

MATERIALS AND METHODS

A total of 121 patients with advanced stage endometriosis and 171 control women were included. Eighteen single-nucleotide polymorphisms (SNPs) from nine genes (HSD17B1, HSD17B2, HSD17B5, HSD17B6, CYP17, CYP19, ERα, ERβ, and PGR) were genotyped using the TaqMan assays. Logistic regression models were used to evaluate the genetic effects, with adjustment for other covariates.

RESULTS

Only the presence of the mutant CYP19 (aromatase gene) was associated with a significantly increased risk of endometriosis after adjusting for age, BMI, and parity (p = 0.002, OR = 2.69; 95% CI = 1.44-5.02). No association was ascertained between the other investigated SNPs and endometriosis.

CONCLUSION

Polymorphisms of the aromatase gene confer susceptibility to advanced stage endometriosis in the Taiwanese Han population.

Polymorphisms in phase I and phase II genes and breast cancer risk and relations to persistent organic pollutant exposure: a case-control study in Inuit women

BACKGROUND

We have previously reported that chemicals belonging to the persistent organic pollutants (POPs) such as perfluorinated compounds (PFAS) and polychlorinated biphenyls (PCBs) are risk factors in Breast Cancer (BC) development in Greenlandic Inuit women. The present case-control study aimed to investigate the main effect of polymorphisms in genes involved in xenobiotic metabolism and estrogen biosynthesis, CYP1A1, CYP1B1, COMT and CYP17, CYP19 and the BRCA1 founder mutation in relation to BC risk and to explore possible interactions between the gene polymorphisms and serum POP levels on BC risk in Greenlandic Inuit women.

METHODS

The study population consisted of 31 BC cases and 115 matched controls, with information on serum levels of POPs. Genotyping was conducted for CYP1A1 (Ile462Val; rs1048943), CYP1B1 (Leu432Val; rs1056836), COMT (Val158Met; rs4680), CYP17A1 (A1> A2; rs743572); CYP19A1 (C> T; rs10046) and CYP19A1 ((TTTA)n repeats) polymorphisms and BRCA1 founder mutation using TaqMan allelic discrimination method and polymerase chain reaction based restriction fragment length polymorphism. The χ2 -test was used to compare categorical variables between cases and controls and the odds ratios were estimated by unconditional logistic regression models.

RESULTS

We found an independent association of CYP1A1 (Val) and CYP17 (A1) with BC risk.Furthermore, an increased BC risk was observed for women with high serum levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) and carriers of at least: one CYP1A1 variant Val allele; one variant COMT Met allele; or the common CYP17 A1 allele. No combined effects were seen between PFAS exposure and CYP1B1 and CYP19 polymorphisms. The risk of BC was not found significantly associated with exposure to PCBs and OCPs, regardless of genotype for all investigated SNPs. The frequency of the Greenlandic founder mutation in BRCA1 was as expected higher in cases than in controls.

CONCLUSIONS

The BRCA1 founder mutation and polymorphisms in CYP1A1 (Val) and CYP17 (A1) can increase the BC risk among Inuit women and the risk increases with higher serum levels of PFOS and PFOA. Serum PFAS levels were a consistent risk factor of BC, but inter-individual polymorphic differences might cause variations in sensitivity to the PFAS/POP exposure.

Polymorphic variants of CYP17 and CYP19A and risk of infertility in endometriosis

OBJECTIVE

Endometriosis is recognized as an estrogen-dependent disease. There are conflicting data demonstrating single nuclear polymorphisms (SNPs) of CYP17 and CYP19 steroidogenic genes as related to endometriosis risk. We assessed the CYP17 5'-untranslated region -34 A/G (rs743572) and CYP19 Ex10 + C1558T (rs10046) SNPs in stage I-II endometriosis.

DESIGN

Case-control study.

SETTING

Division of reproduction at a university department in Poland.

POPULATION

A total of 115 women with diagnosed stage I-II endometriosis according to the revised American Society for Reproductive Medicine (rASRM) classification and 197 fertile women as controls.

METHODS

The SNPs CYP17 -34 A/G and CYP19 Ex10 + C1558T were identified by high-resolution melting curve analysis.

MAIN OUTCOME MEASURES

Genotype prevalence and odds ratio for recessive and dominant genetic model for CYP17 and CYP19 SNPs.

RESULTS

We observed a significantly increased CYP17 GG and GA genotype frequency in women diagnosed with rASRM stage I-II endometriosis compared with fertile women (OR = 2.4; 95% CI 1.4-4.2, p = 0.002). We also found a significantly increased CYP17 G allele frequency in cases compared with controls (OR = 1.6; 95% CI 1.2-2.2, p = 0.004). There were no significant differences in the distribution of the CYP17 GG genotype and CYP19 Ex10 + C1558T polymorphism between women diagnosed with rASRM stage I-II endometriosis and controls.

CONCLUSION

The CYP17 -34 G variant, previously associated with increased 17β-estradiol production, displayed a contribution to stage I-II endometriosis in women from a Polish population. Increased 17β-estradiol concentration in carriers of the CYP17 -34 G variant might contribute to endometriosis and associated pathological processes.

Genetic variation in the sex hormone metabolic pathway and endometriosis risk: an evaluation of candidate genes

OBJECTIVE

To evaluate the relationship between common genetic variation in genes involved in the biosynthesis and signaling of estrogen and progesterone and endometriosis risk.

DESIGN

Genetic polymorphism analysis.

SETTING

Population-based case-control study conducted in Group Health Cooperative enrollees in western Washington.

PATIENT(S)

Women with newly diagnosed, surgically confirmed endometriosis between 1996 and 2001 (n = 256) and age- and reference year-matched female control subjects without a history of endometriosis (n = 567).

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

We evaluated the relationship between common genetic variation and endometriosis risk, using gene-based tests and single-variant analysis of genetic polymorphisms in ESR1, ESR2, PGR, CYP17A1, CYP19A1, HSD17B1, HSD17B2, CYP1A1, CYP1A2, COMT, and GSTM1.

RESULT(S)

The most consistent gene-based association with endometriosis risk was for CYP19A1. We did not find evidence for consistent significant associations between previously reported candidate SNPs in sex hormone-related genes and endometriosis risk.

CONCLUSION(S)

In summary, we report increased endometriosis risk with CYP19A1 gene-based tests; replication of the association between endometriosis and this gene or gene region is necessary in a larger study population.

Role of CYP2C19 polymorphisms in patients with endometriosis

AIM

To investigate the association of CYP2C19 genotypes with endometriosis.

METHODS

The study included 100 women who underwent laparotomy or laparoscopy: 50 patients with endometriosis diagnosed with surgery and histopathology, and 50 control subjects who had no evidence of endometriosis during exploratory laparotomy or laparoscopy. Genomic DNA of subjects was extracted from the whole blood using High Pure PCR template preparation kit. Genotyping of CYP2C19 polymorphisms were detected by using a LightCycler CYP2C19 mutation detection kit in a real-time PCR, and were compared between the two groups.

RESULTS

Logistic regression analyses showed that the CYP2C19*2 heterozygote genotype was associated with a significantly increased risk of endometriosis. The odds ratio of endometriosis for the CYP2C19*2 heterozygote genotype was 3.165 (p = 0.023) compared with the control group. CYP2C19*3 genotype was detected as wild in all subjects in the endometriosis and control groups.

CONCLUSION

Our results suggest that CYP2C19*2 heterozygote genotype has higher risk of developing endometriosis. Therefore, CYP2C19*2 allele gene polymorphisms may be associated with genetic susceptibility of endometriosis.

CYP17 and CYP19 gene polymorphisms in women affected with endometriosis

OBJECTIVE

To investigate whether CYP17 T>C polymorphism and polymorphisms C1558T and Val80 of CYP19 are related to endometriosis.

DESIGN

Clinical study.

PATIENT(S)

Women affected with endometriosis (n = 104) and control group (n = 86). The diagnosis of endometriosis was confirmed by the histologic examination of the endometriotic lesions.

RESULT(S)

In patients affected with endometriosis, we observed that AA and CC genotypes were significantly represented in Val80 and C1558T polymorphisms of CYP19.

CONCLUSION(S)

The molecular mechanisms that underlie the development of endometriosis are unclear. Both environmental and genetic factors are involved in the pathogenesis of the disease. The inheritable susceptibility to endometriosis justifies the growing interest in identifying genes and/or genetic polymorphisms that predispose women to an increased risk of developing endometriosis. The identification of single-nucleotide polymorphism (SNP), probably linked to endometriosis, could help to explain its pathogenesis.

Common Variation in the CYP17A1 and IFIT1 Genes on Chromosome 10 Does Not Contribute to the Risk of Endometriosis

Endometriosis is a complex disease involving multiple susceptibility genes and environmental factors. Our previous studies on endometriosis identified a region of significant linkage on chromosome 10q. Two biological candidate genes (CYP17A1 and IFIT1) located on chromosome 10q, have previously been implicated in endometriosis and/or uterine function. We hypothesized that variation in CYP17A1 and/or IFIT1 could contribute to the risk of endometriosis and may account for some of the linkage signal on chromosome 10q. We genotyped 17 single nucleotide polymorphisms (SNPs) in the CYP17A1 and IFIT1 genes including SNP rs743572 previously associated with endometriosis in 768 endometriosis cases and 768 unrelated controls. We found no evidence for association between endometriosis and individual SNPs or SNP haplotypes in CYP17A1 and IFIT1. Common variation in these genes does not appear to be a major contributor to endometriosis susceptibility in our Australian sample.

Functional genetic polymorphisms and female reproductive disorders: part II--endometriosis

BACKGROUND

Endometriosis has a strong genetic component, and numerous genetic studies have been reported.

METHODS

We have systematically reviewed these studies and included 114 in our final selection.

RESULTS

We found no consistent evidence linking endometriosis with specific polymorphisms in genes encoding inflammatory mediators, proteins involved in sex steroid metabolism, vascular function and tissue remodelling. Although a number of polymorphisms have been associated with endometriosis in selected populations, the associations have not been independently confirmed, either because only single studies were carried out on these markers/genes or because other studies reported no association. The most solid evidence linking specific polymorphisms to endometriosis came from studies investigating glutathione-S-transferase, a phase II detoxification enzyme. Carriage of the GSTT1 null deletion variant showed consistent association with endometriosis with a 29% increased risk; however, it cannot be excluded that this result was due to publication bias, and this association should be independently confirmed in large-scale, well-designed case–control studies.

CONCLUSIONS

The evidence of an association between genetic polymorphisms and endometriosis is weak. Carriage of the GSTT1 null deletion may moderately increase the risk of this disease. We suggest that the methodology of association studies should be improved in order to identify and validate associations in endometriosis.

Endometriosis and Genetic Polymorphisms

Endometriosis is a benign gynecological disease with an unclear pathophysiology characterized by ectopic endometrium causing endometrium-like inflammatory lesions outside the uterine cavity. Recently, a number of studies have investigated genetic polymorphisms as a possible factor contributing to the development of endometriosis. In this review, we have summarized current data regarding genes with nucleotide polymorphisms investigated with regard to endometriosis. We searched PubMed for publications on endometriosis and polymorphism and found 108 publications between January 1979 and September 2005. These were classified according to the type of genetic polymorphism investigated and whether the result favored or did not favor association with endometriosis. We found a strikingly large amount of conflicting results. About 50% of the reviewed studies demonstrated positive correlations between different polymorphisms and endometriosis. This relation is most clearly seen in groups 1 (cytokines and inflammation), 2 (steroid-synthesizing enzymes and detoxifying enzymes and receptors), 4 (estradiol metabolism), 5 (other enzymes and metabolic systems), and 7 (adhesion molecules and matrix enzymes). Group 8 (apoptosis, cellcycle regulation, and oncogenes) seemed to be negatively correlated with the disease, whereas group 3 (hormone receptors), 6 (growth factor systems), and especially 9 (human leukocyte antigen system components) showed a relatively strong correlation. The review indicates that polymorphisms may have a limited value in assessing possible development of endometriosis.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall the complexity of attempting to link endometriosis to single nucleotide polymorphisms (SNPs), explain that the literature is varied on results and recommendations and is population specific, and state that there are some SNP relationships that are clinically stronger than others.

Description of a novel polymorphic gene encoding for arylamine N-acetyltransferase in the rhesus macaque (Macaca mulatta), a model animal for endometriosis

OBJECTIVES

Case-control studies have previously associated polymorphisms in the gene encoding the xenobiotic metabolizing enzyme arylamine N-acetyltransferase 2 (NAT2) with endometriosis, a common multifactorial disease in women. These studies, however, have been problematic on methodological grounds and their results are inconclusive. To better understand the possible relationship between the NAT2 gene and endometriosis, we characterized its homologue in the rhesus macaque, an animal model for the disease.

METHODS

Human NAT2-specific primers were used to isolate orthologous gene sequences from four unrelated rhesus macaques of the same colony. Recombinant proteins were expressed in mammalian cells and analysed for their ability to acetylate NAT substrates and bind anti-NAT antibodies.

RESULTS

A polymorphic gene, showing 94% identity to human NAT2, was identified in the rhesus macaque. Its two characterized alleles, designated (MACMU)NAT2*1 and (MACMU)NAT2*2, were differentiated by one synonymous (C(624)T) and one nonsynonymous (G(691)A) polymorphism, the latter causing a Val(231)Ile substitution. The recombinant (MACMU)NAT2 protein was not recognized by anti-(HUMAN)NAT1 antibody, but reacted with antibodies against (HUMAN)NAT2 or the active site of NAT. Rhesus NAT2 provided relatively high acetylation activity with p-anisidine, lower activity with procainamide, sulphamethazine or 5-aminosalicylate and poor activity with p-aminobenzoic acid. Differences in the activities of the two allozymes were evident with most substrates.

CONCLUSIONS

A polymorphic homologue of human NAT2 was characterized in the rhesus macaque, to facilitate investigations of the postulated involvement of this isoenzyme in the toxicogenetics of endometriosis.

Genetic polymorphisms of cytochrome P450cl7alpha (CYP17) and progesterone receptor genes (PROGINS) in the assessment of endometriosis risk

We designed the present study in order to evaluate the eventual role of polymorphisms in the genes encoding cytochrome P450c17alpha (CYP17) and the progesterone receptor (PROGINS) as risk factors for endometriosis development. Eligible cases consisted of 121 women with surgically confirmed endometriosis who underwent treatment in a hospital in São Paulo, Brazil during the period from September 2003 to September 2005. The 281 controls were participants with normal gynecological as well as pelvic ultrasound evaluation, who did not have any gynecological conditions during their reproductive lives such as pelvic pain and/or dyspareunia nor infertility history. Genomic DNA was obtained from buccal cells and processed for DNA extraction using the GFX DNA extraction kit (GE Healthcare). The CYP17 (-34T-->C) polymerase chain reaction-restriction fragment length polymorphism assay has been described previously, as has the progesterone receptor polymorphism (PROGINS) detection assay. PROGINS heterozygosis genotype frequencies were shown to be statistically higher in endometriosis cases compared with controls. On the other hand, differences in the CYP17 polymorphism (-34T-->C) frequencies were not even close to significance (p = 0.278) according to our findings.

CYP17, CYP1A1 and COMT polymorphisms and the risk of adenomyosis and endometriosis in Taiwanese women

BACKGROUND

The aim of the study was to test whether the COMT, CYP1A1 and CYP17 genes influence the risk of developing adenomyosis and endometriosis.

METHODS

We conducted two case-control studies, where the cases (n = 198) had either of the two diseases, and controls (n = 312) were disease-free women. For the COMT gene, we selected the G/A nonsynonymous single-nucleotide polymorphism (SNP) that leads to valine-to-methionine (Val/Met) substitution. For the CYP1A1 gene, we used a functional T/C SNP in the 3'-noncoding region, and we genotyped a T/C functional SNP in the 5' region of the CYP17 gene for the present study. Hardy-Weinberg equilibrium was checked in both cases and controls. Logistic regression models were used to evaluate the genetic effect, with adjustment for other covariates.

RESULTS

We found that the homozygous COMT genotype that encodes low enzyme activity had an increased risk for adenomyosis with an age-adjusted odds ratio of 3.2 (95% confidence interval 1.3-7.8; P = 0.006). The COMT gene, however, was not associated with endometriosis. Neither the CYP1A1 nor CYP17 genes had any significant association with either of the two diseases.

CONCLUSION

The COMT gene significantly influences the risk of adenomyosis but not endometriosis. The present study does not provide evidence to support any of the three genes exerting pleiotropic effects on both diseases.

Association of endometriosis risk and genetic polymorphisms involving sex steroid biosynthesis and their receptors: a meta-analysis

Endometriosis is a sex steroids-dependent disease. It has been postulated that certain genetic polymorphisms involved in sex steroids biosynthesis and metabolisms may be associated with increased risk of developing endometriosis. Despite a deluge of reports of positive associations of endometriosis with numerous polymorphisms involving sex steroids production and metabolism, the results are often conflicting. We performed a meta-analysis of 12 association studies on 5 genes (CYP17, CYP19, AR, PR and ER). We found that many reported positive findings were not supported by the data due to faulty analysis. There have been no functional data that support a putative relationship of these genetic polymorphisms with endometriosis. A handful of positive findings so far have not been independently replicated, and should be viewed as preliminary. In addition, these findings should be counterbalanced by legitimate concerns of multiple comparisons, small prior probability of association with a particular polymorphism, proper selection of controls, and lack of replication (at least until now). In future association studies, it may be productive to put more thought to study design, execution, and data analysis.