Whole-exome sequencing reveals candidate high-risk susceptibility genes for endometriosis

BACKGROUND

Endometriosis is a common, chronic disease among fertile-aged women. Disease course may be highly invasive, requiring extensive surgery. The etiology of endometriosis remains elusive, though a high level of heritability is well established. Several low-penetrance predisposing loci have been identified, but high-risk susceptibility remains undetermined. Endometriosis is known to increase the risk of epithelial ovarian cancers, especially of endometrioid and clear cell types. Here, we have analyzed a Finnish family where four women have been diagnosed with surgically verified, severely symptomatic endometriosis and two of the patients also with high-grade serous carcinoma.

RESULTS

Whole-exome sequencing revealed three rare candidate predisposing variants segregating with endometriosis. The variants were c.1238C>T, p.(Pro413Leu) in FGFR4, c.5065C>T, p.(Arg1689Trp) in NALCN, and c.2086G>A, p.(Val696Met) in NAV2. The only variant predicted deleterious by in silico tools was the one in FGFR4. Further screening of the variants in 92 Finnish endometriosis and in 19 endometriosis-ovarian cancer patients did not reveal additional carriers. Histopathology, positive p53 immunostaining, and genetic analysis supported the high-grade serous subtype of the two tumors in the family.

CONCLUSIONS

Here, we provide FGFR4, NALCN, and NAV2 as novel high-risk candidate genes for familial endometriosis. Our results also support the association of endometriosis with high-grade serous carcinoma. Further studies are required to validate the findings and to reveal the exact pathogenesis mechanisms of endometriosis. Elucidating the genetic background of endometriosis defines the etiology of the disease and provides opportunities for expedited diagnostics and personalized treatments.

Genetic, Epigenetic, and Steroidogenic Modulation Mechanisms in Endometriosis

Endometriosis is a chronic gynecological disease, affecting up to 10% of reproductive-age women. The exact cause of the disease is unknown; however, it is a heritable condition affected by multiple genetic, epigenetic, and environmental factors. Previous studies reported variations in the epigenetic patterns of numerous genes known to be involved in the aberrant modulation of cell cycle steroidogenesis, abnormal hormonal, immune and inflammatory status in endometriosis, apoptosis, adhesion, angiogenesis, proliferation, immune and inflammatory processes, response to hypoxia, steroidogenic pathway and hormone signaling are involved in the pathogenesis of endometriosis. Accumulating evidence suggest that various epigenetic aberrations may contribute to the pathogenesis of endometriosis. Among them, DNA methyltransferases, histone deacetylators, and non-coding microRNAs demonstrate differential expression within endometriotic lesions and in the endometrium of patients with endometriosis. It has been indicated that the identification of epigenetic differences within the DNA or histone proteins may contribute to the discovery of a useful prognostic biomarker, which could aid in the future earlier detection, timely diagnosis, and initiation of a new approach to the treatment of endometriosis, as well as inform us about the effectiveness of treatment and the stage of the disease. As the etiology of endometriosis is highly complex and still far from being fully elucidated, the presented review focuses on different approaches to identify the genetic and epigenetic links of endometriosis and its pathogenesis.

Familial deep endometriosis: A rare monogenic disease?

Endometriosis is a frequent cause of pelvic pain and subfertility in women of reproductive age. Presence of extra-uterine endometrial-like tissue is responsible for non-specific symptoms such as chronic pelvic pain, dysmenorrhea, dyspareunia, dyschesia and sometimes infertility. Three different phenotypes according to the location of the lesions are described, namely peritoneal, ovarian and deep infiltrating endometriosis. Deep endometriosis is considered as a distinct homogeneous disease. Heritability of endometriosis has been previously demonstrated. Despite extensive efforts to characterize candidate alleles contributing to genetic basis of endometriosis, these factors relevant to endometriosis pathophysiology remain unclear. No high penetrance pathogenic variant could be identified. We report herein two families with familial aggregation of severe deep infiltrating endometriosis, providing further evidence for monogenic mendelian inheritance of this form of endometriosis.

Primary Open-Angle Glaucoma Genetics in African Americans

PURPOSE OF REVIEW

Individuals of African descent are at highest risk for developing primary open-angle glaucoma (POAG), a devastating disease and major contributor of blindness worldwide. Currently, there is a large dearth of knowledge in this area despite a critical need for better understanding the underlying genetic and environmental factors afflicting this population. Here we highlight the current literature exploring the genetics of POAG in African Americans.

RECENT FINDINGS

Current studies have yet to replicate European POAG index variants (i.e. CDKN2B-AS1 and SIX1/SIX6) in African Americans or to definitely exclude that these loci contribute to risk in African descent populations. Recent studies have evaluated clinical features that may account for some differences in POAG risk between African Americans and European Americans.

SUMMARY

In summary, little headway has been made in elucidating the genetics of primary open-angle glaucoma in African Americans and other individuals of African descent.

Genetic association study in a three-generation family with seven members with endometriosis

The aim of this study was to investigate whether five single nucleotide polymorphisms (SNPs), associated with endometriosis, may confer new insight towards a genotype‑phenotype association with endometriosis. We studied a three-generation family with seven women who had endometriosis. Blood specimens were obtained from all the affected female family members. The entire family was genotyped for five SNPs mapped to WNT4, VEZT, FSHB and IL-16 genetic loci. We further evaluated the members of the family with endometriosis and described all obstetric and gynecological complications caused by the disease in these seven women. The five SNPs analyzed did not reveal any genotype-phenotype correlation with the disease. The members of the family with endometriosis showed a variety of clinical manifestations and complications. None of the five genetic markers examined correlated genotype with phenotype in the case of the Greek three-generation family examined. Therefore, we conclude that more gene polymorphisms must be investigated in the members of this family to gain insight regarding a genotype‑phenotype correlation in endometriosis and the potential development of a personalized care for the patients based on these data.