Glutathione S-transferase M1 and T1 gene polymorphisms in Brazilian women with endometriosis

CYP19A1 TC/CC Polymorphism, along with Deletion of GSTM1 and GSTT1 Genes, Strongly Influences Female Infertility Risk

Oxidative stress has a fundamental role in the pathophysiology of various conditions, like infertility. This case-control study was performed to assess the potential role of CYP19A1, GSTM1, and GSTT1 in modifying individual predisposition to female infertility. Genotyping of 201 women with established infertility and 161 fertile female controls was performed, and statistical associations were analyzed. For carriers of GSTM1 null genotype along with CYP19A1 C allele, there is a significant association with female infertility risk (OR 7.023; 95% CI (3.627-13.601; p < 0.001), and, also for carriers of GSTT1 null genotype along with the CYP19A1 TC/CC genotype (OR 24.150; 95% CI (11.148-52.317; p < 0.001). A positive association with female infertility risk for carriers of the C allele in CYP19A1 and null genotypes in GTSM1 (OR 11.979; 95% CI (4.570-31.400; p < 0.001) or GSTT1 (OR 13.169; 95% CI (4.518-38.380; p < 0.001) was found. When both GSTs are deleted, the risk of developing female infertility is significant, independently of the CYP19A1 genotype; when all the presumed high-risk genotypes are present, we found a significant association with female infertility risk (OR 47,914; 95% CI (14,051-163,393; p < 0.001).

Polymorphisms of the GSTT1 and GSTM1 genes in polycystic ovary syndrome

SUMMARY BACKGROUND: This study aimed to investigate the deletion polymorphisms of the genes of the glutathione S-transferase family GSTT1 and GSTM1 in patients with Polycystic Ovarian Syndrome (PCOS), comparing them with a control population. METHODS: Blood was collected from 219 women (110 with PCOS and 109 controls) and genomic DNA was extracted. For the analysis of polymorphisms, the technique used was multiplex PCR. In the statistical analysis, the chi-square test and multiple logistic regression were used. RESULTS: There is no association between the GSTM1 null and GSTT1 null genotypes with PCOS when analyzed separately (P = 0.616 and P = 0.188). The analysis of the combined genotypes showed differences between the groups (P < 0.05), evidencing that the genotypic combination GSTT1 positive and GSTM1 negative is more frequent among patients. In the multivariate analysis, smoking was more frequent in the control group (OR = 0.22; 95% CI - 0.87-0.57; P = 0.002) while the presence of a family history of PCOS (OR = 2, 96; 95% CI - 1.54-5.68; P = 0.001) was more frequent in women with PCOS. CONCLUSIONS: In the studied sample, the deletion polymorphisms of the GSTT1 and GSTM1 genes isolated are not associated with PCOS, but in combination, they may be implicated in the etiology of the condition.

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.

Women with polycystic ovary syndrome and other causes of infertility have a higher prevalence of GSTT1 deletion

RESEARCH QUESTION

Is GSTM1 and GSTT1 deletion associated with the development of polycystic ovary syndrome (PCOS)?

DESIGN

A case-control study was designed to investigate the association between GSTM1 and GSTT1 gene polymorphisms with PCOS. Blood samples from 201 women diagnosed with infertility were taken, of which 69 women were diagnosed with PCOS. Genomic DNA was extracted, and genotyping analyses were conducted by polymerase chain reaction-based methods. Odds ratios and 95% confidence intervals were calculated by unconditional logistic regression.

RESULTS

An increased risk of PCOS was found to be associated with GSTT1 null genotype (OR 4.890, 95% CI 2.261 to 9.122; P < 0.001). A strong association between GSTT1 null genotype was found with female infertility, regardless of the associated cause (OR 5.300, 95% CI 3.238 to 8.675; P < 0.001) as well as with the GSTM1 null genotype (OR 1.620, 95% CI 1.067 to 2.459; P = 0.026). A statistically significant association with the development of infertility was also found when carriers of the combined genotype GSTT1+/GSTM1+ was compared with carriers of the combined genotype GSTT1-/ GSTM1+ (OR 3.600 95% CI 1.864 to 6.956; P < 0.001). The two-way combination of GSTT1 and GSTM1 null genotypes resulted in an increased susceptibility to infertility development (OR 11.136; 95% CI 5.035 to 24.629; P < 0.001).

CONCLUSIONS

Carriers of GSTT1 null genotype seem to have higher susceptibility to developing PCOS and infertility from other causes. Also, GSTT1 null genotype, alone or in association, are related with increased susceptibility to infertility development, independently of its cause. GSTM1 null genotype is only associated with all cause of infertility when the GSTT1 is null.

The importance of understanding the distribution of GSTM1 and GSTT1 genotypes and haplotypes in a region with intense agriculture activity

Brazil is one of the largest pesticide consumers in the world, mainly due to its intense agricultural activity. The State of Goias, situated in Central Brazil, is a region recognized as an essential producer of soy, corn, beans, sorghum, sugar cane, and cotton. In this study, we evaluated 602 unrelated individuals, distributed in central and southern regions in Goias, presenting combined frequencies (haplotypes) of the GSTT1 and GSTM1 genes. In all municipalities, the frequency of the GSTT1 null genotype was 38.2% and of the GSTM1 null genotype was 50.3%. Goiania, the capital of Goias, presented the highest frequencies of GSTT1 and GSTM1 null genotypes, probably due to a founder effect of non-representative colonizing ancestors. So, the ancestral population adapted to the environment, with the frequencies observed in Goiania. However, nowadays, as there is excessive use of pesticides, the community becomes susceptible to the harmful effects of xenobiotics exposure, mainly due to the high frequency of GSTT1 and GSTM1 null genotypes. As in Goias, the consumption of pesticides has shown considerable growth, haplotypes with null alleles are of high risk for the population. Our results indicated that it is essential to understand the frequencies of the GSTT1 and GSTM1 genes for the monitoring of risk groups, like farmers, who have contact with pesticides, directly or indirectly, as well as assisting in the development of preventive medicine practices.

Defining the genetic profile of endometriosis

Endometriosis is a pathological condition which has been extensively studied, since its pathophysiology stems from a broad spectrum of environmental influences and genetic factors. Familial studies aim at defining inheritance trends, while linkage analysis studies focus on the identification of genetic sites related to endometriosis susceptibility. Genetic association studies take into account candidate genes and single nucleotide polymorphisms, and hence target at unraveling the association between disease severity and genetic variation. The common goal of various types of studies is, through genetic mapping methods, the timely identification of therapeutic strategies for disease symptoms, including pelvic pain and infertility, as well as efficient counselling. While genome-wide association studies (GWAS) play a primary role in depicting genetic contributions to disease development, they entail a certain bias as regards the case-control nature of their design and the reproducibility of the results. Nevertheless, genetic-oriented studies and the implementation of the results through clinical tests, hold a considerable advantage in proper disease management. In this review article, we present information about gene-gene and gene-environment interactions involved in endometriosis and discuss the effectiveness of GWAS in identitying novel potential therapeutic targets in an attempt to develop novel therapeutic strategies for a better management and treatment of patients with endometriosis.