Plasma miR-17-5p, miR-20a and miR-22 are down-regulated in women with endometriosis.

STUDY QUESTION Can plasma microRNAs be used as a non-invasive diagnostic test for the detection of endometriosis? SUMMARY ANSWER Plasma miR-17-5p, miR-20a and miR-22 are down-regulated in women with endometriosis compared with those without endometriosis in mainland China. WHAT IS KNOWN ALREADY There is currently a pressing need to develop a non-invasive diagnostic test for endometriosis. Altered circulating microRNA profiles have already been linked to various disease states. STUDY DESIGN, SIZE, AND DURATION This was a prospective laboratory study in a tertiary-referral university hospital in Beijing, PR China, between January 2012 and May 2012. Twenty-three women with histologically proven endometriosis and 23 endometriosis-free controls were enrolled in this study. PARTICIPANTS/MATERIALS, SETTING, AND METHODS Laparoscopic inspection of the abdominopelvic cavity was performed for each patient, and peripheral blood samples were collected before laparoscopy. Microarray-based microRNA expression profiling was used to identify differentially expressed microRNAs in plasma samples between women with and without endometriosis, and quantification of selected microRNAs was performed using quantitative RT-PCR. MAIN RESULTS AND THE ROLE OF CHANCE Twenty-seven microRNAs were differentially expressed between women with and without endometriosis, of which six microRNAs (miR-15b-5p, miR-17-5p, miR-20a, miR-21, miR-22 and miR-26a) were selected for validation. MiR-17-5p, miR-20a and miR-22 were significantly down-regulated in women with endometriosis compared with controls (P = 0.011, 0.0020 and 0.0002, respectively), yielding an area under the receiver operator characteristics curve of 0.74 [95% confidence interval (CI): 0.58-0.90], 0.79 (95% CI: 0.65-0.93) and 0.85 (95% CI: 0.71-0.98) in discriminating endometriosis from controls, respectively. LIMITATIONS AND REASONS FOR CAUTION Our sample size was small and all cases were rAFS stage III-IV, which may limit generalization of plasma microRNAs for early diagnosis of endometriosis. Moreover, only six microRNAs were selected for validation. WIDER IMPLICATIONS OF THE FINDINGS Plasma microRNAs provide a promising opportunity for detection of endometriosis.