Chromosomal aberrations detected by chromogenic in situ hybridization in abdominal wall endometriosis after cesarean section

Somatic Genomic Events in Endometriosis: Review of the Literature and Approach to Phenotyping

In this review, we provide a survey and appraisal of research into somatic genomic events in endometriosis. Methodologies have evolved from conventional cytogenetics to next-generation sequencing, with findings ranging from chromosome imbalances to recurrent somatic cancer driver mutations. Somatic cancer driver mutations have been described in a range of endometriosis lesions, dominated by recurrent mutations in KRAS and PIK3CA as well as loss of PTEN and BAF250a (ARID1A). These somatic events appear to be largely restricted to the endometriosis glandular epithelium. Somatic mutations, particularly PTEN loss, have also been observed in eutopic (uterine) endometrium, although at lower mutant allele frequencies compared with ectopic lesions. Systematic studies of the potential clinical phenotype of these somatic genomic events have yet to be performed. Thus, we propose a framework to investigate the potential clinical phenotype associated with somatic genomic events in endometriosis. Technical requirements include pathology review of histological endometriosis, microdissection for tissue enrichment, orthogonal validation of whole genome/exome sequencing, and a germline sample for confirmation of somatic origin. Clinical requirements include annotation of surgical findings; patient demographics; cross-sectional and prospective data on pain and fertility; consideration of sampling multiple lesions in each patient, mutant allele frequency, and somatic events in the eutopic endometrium; and confirmation of any associations with mechanistic studies. Given the multifactorial nature of endometriosis-associated symptoms, it is likely that somatic events have small (or at most, moderate) effect sizes, and thus careful consideration will have to be given to future study design.

Genetic, epigenetic and stem cell alterations in endometriosis: new insights and potential therapeutic perspectives

Human endometrium is a highly dynamic tissue, undergoing periodic growth and regression at each menstrual cycle. Endometriosis is a frequent chronic pathological status characterized by endometrial tissue with an ectopic localization, causing pelvic pain and infertility and a variable clinical presentation. In addition, there is well-established evidence that, although endometriosis is considered benign, it is associated with an increased risk of malignant transformation in approximately 1.0% of affected women, with the involvement of multiple pathways of development. Increasing evidence supports a key contribution of different stem/progenitor cell populations not only in the cyclic regeneration of eutopic endometrium, but also in the pathogenesis of at least some types of endometriosis. Evidence has arisen from experiments in animal models of disease through different kinds of assays (including clonogenicity, the label-retaining cell approach, the analysis of undifferentiation markers), as well as from descriptive studies on ectopic and eutopic tissue samples harvested from affected women. Changes in stem cell populations in endometriotic lesions are associated with genetic and epigenetic alterations, including imbalance of miRNA expression, histone and DNA modifications and chromosomal aberrations. The present short review mainly summarizes the latest observations contributing to the current knowledge regarding the presence and the potential contribution of stem/progenitor cells in eutopic endometrium and the aetiology of endometriosis, together with a report of the most recently identified genetic and epigenetic alterations in endometriosis. We also describe the potential advantages of single cell molecular profiling in endometrium and in endometriotic lesions. All these data can have clinical implications and provide a basis for new potential therapeutic applications.