The study finding that the plasma miRNAs as biomarkers for endometriosis; as endometriosis, defining as the presence of endometrial like tissue outside the uterus; is a chronic gynaecological disease with an overall prevalence of 2–10% in women of reproductive age and up to 50% in infertile women. Patients with endometriosis can be asymptomatic but typically present with chronic pelvic pain, infertility or both.
But due to its chronic character, lack of medical treatment and debilitating symptoms; endometriosis results in major public health care costs, comparable to that of Crohn’s disease. The study involving that by investigating whether plasma miRNAs can be using for the non-invasive diagnosis of endometriosis. First, we identified a set of 42 plasma miRNAs with discriminative potential between patients with and without endometriosis based on a genome-wide miRNA expression profiling.
Secondly, we validated miRNA expression with RT-qPCR and developing three diagnostic models in the discovery cohort of 120 patients. Staging of endometriosis was done by two experienced endometriosis surgeons, again minimizing potential variability. The use of standard protocols for both clinical management and sample collection allowed us to minimize the clinical and technical variability in the two patient cohorts.
Biomarkers for endometriosis
But the study workflow with highly validating standard operating procedures for miRNA expression analysis and data processing to maximize the accuracy of our results. In the discovery phase, we used next generation sequencing for miRNA expression analysis. This state-of-the art technology is ideal for unbiased genome-wide miRNA expression profiling.
For the development and validation of the diagnostic models, we used RT-qPCR; that has high specificity and linear dynamic range of quantification, making it the gold standard for expression profiling of even low abundant miRNAs. Normalization of miRNA expression data is challenging since no standard reference or housekeeping miRNAs have been identifying.
Potential of plasma miRNAs
However, by finding the potential of plasma miRNAs as biomarkers for endometriosis in women; with infertility and pain. Our study supports a possible biological link between certain miRNAs. The potential of these miRNAs as clinically useful biomarkers; is questionable given the important individual natural variation in miRNA levels.
The stage III–IV group is more heterogenous since it consists of patients with extensive adhesions; endometriomas, deep endometriotic nodules, etc., whereas patients in the stage I–II group almost exclusively have peritoneal endometriosis and sometimes limited adhesions. Large studies in well-described patient cohorts; with rigorous methodology for miRNA expression analysis, sufficient statistical power and an independent validation step, are necessary to answer the question of whether miRNAs can be used for the non-invasive diagnosis of endometriosis.