Interleukin-2 receptor beta gene C627T polymorphism in Korean women with endometriosis: a case-control study

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.

Epidemiologic Factors Associated with Endometriosis in East Asia

Aim

With a perplexing pathogenesis and an incidence rate of approximately 10% among women of reproductive age, endometriosis affects more women in Asia than in any other continent in the world. This paper reviews the available data on the epidemiology and risk factors associated with endometriosis in East Asia.

Methods

Included studies were published between January 2000 and December 2016. Articles were required to include East Asian patients with a diagnosis of endometriosis and to study epidemiology, such as the prevalence and/or incidence, associated with inherited, environmental, and/or lifestyle factors. A total of 65 candidate articles were retrieved and 22 were included in the final review.

Results

Only one study provided an estimate of prevalence (6.8%). Short menstrual cycle, family history of endometriosis, and some genetic polymorphisms are associated with the risk of developing endometriosis. Smoking, lower body mass index, and lower parity associated with increased risk of endometriosis were suggested as modifiable factors. Limitations of this study include the poor quality of data identified, and the language barriers behind the study retrieval.

Conclusions

Data on the epidemiology of endometriosis in the East Asian populations are limited. The available data that examine potential genetic factors do not unveil whether such factors directly contribute to the increased risk of endometriosis. Further extensive studies on endometriosis in Asian women are required to improve the management of this disease.

Interplay between Misplaced Müllerian-Derived Stem Cells and Peritoneal Immune Dysregulation in the Pathogenesis of Endometriosis

In the genetic regulation of Müllerian structures development, a key role is played by Hoxa and Wnt clusters, because they lead the transcription of different genes according to the different phases of the organogenesis, addressing correctly cell-to-cell interactions, allowing, finally, the physiologic morphogenesis. Accumulating evidence is suggesting that dysregulation of Wnt and/or Hox genes may affect cell migration during organogenesis and differentiation of Müllerian structures of the female reproductive tract, with possible dislocation and dissemination of primordial endometrial stem cells in ectopic regions, which have high plasticity to differentiation. We hypothesize that during postpubertal age, under the influence of different stimuli, these misplaced and quiescent ectopic endometrial cells could acquire new phenotype, biological functions, and immunogenicity. So, these kinds of cells may differentiate, specializing in epithelium, glands, and stroma to form a functional ectopic endometrial tissue. This may provoke a breakdown in the peritoneal cavity homeostasis, with the consequent processes of immune alteration, documented by peripheral mononuclear cells recruitment and secretion of inflammatory cytokines in early phases and of angiogenic and fibrogenic cytokines in the late stages of the disease.

Insights into Assessing the Genetics of Endometriosis

Endometriosis is a complex disease arising from the interplay between multiple genetic and environmental factors. The genetic variants potentially underlying the hereditary component of endometriosis have been widely investigated through hypothesis-driven candidate gene studies, an approach that generally has proven to be inherently difficult and problematic for a number of reasons. Recently, through major collaborative efforts in the endometriosis research field, hypothesis-free genome-wide approaches have started to provide new insights into potential pathways leading to development of endometriosis, as well as highlighting the phenotypic heterogeneity of the condition. This review summarizes the most recent studies investigating the genetic variation contributing to endometriosis, with a particular focus on genome-wide approaches, and discusses promising future directions of genetic research.

T-cell receptor beta polymorphism is not associated with endometriosis

AIM

We carried out an association study between T-cell receptor beta polymorphism (TCRB) and endometriosis to investigate the difference in allelic frequency. Polymorphisms in T-cell receptor genes can provide important information for the study of the immune response and autoimmune diseases; indeed, rs1800907, a very common single nucleotide polymorphism (SNP) of the TCRB, has been extensively studied in autoimmune diseases in the 1990s using Southern blot analysis and more recently polymerase chain reaction (PCR) and sequencing. An autoimmune etiology for endometriosis has been strongly suggested for the presence of antibodies against endometrium, high rates of autoimmune disorders and associated atopic diseases.

MATERIAL AND METHODS

We investigated 70 patients with endometriosis and 120 controls. DNA of patients and controls was studied by PCR followed by restriction digestion and sequencing to determine genotype and presence of linkage disequilibrium (LD). Statistical analysis was carried out using STATA Routine GENHW (StataCorp, College Station, TX, USA) for estimation of Hardy-Weinberg equilibrium and test power calculation. The difference of allele distribution between patients and controls was calculated according to Pearson's and Fisher's tests. Test power for the estimation of linkage disequilibrium is low (0.16).

RESULTS

We performed an association study of the SNP rs1800907 of TCRB between 70 patients with endometriosis and 120 controls, and did not find any significant difference (χ(2) = 0.27 and P = 0.87). Fisher's test confirmed a P-value of 0.872.

CONCLUSION

Our study does not suggest an evidential and major involvement of TCRB in the pathogenesis of endometriosis in an Italian population in a small case control study.