Jiang X, Li J, Zhang B, et al. - Researchers investigated different expression profiles of plasma exosomal microRNA (miRNA) in polycystic ovary syndrome (PCOS) patients and controls. In addition, they determined their potential roles in PCOS pathogenesis. Plasma exosomes miRNAs were sequenced from 15 PCOS patients and 15 controls. The miRNA sequencing revealed differential expression of 34 exosomal miRNAs between PCOS patients and controls. Via quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), they identified five differentially expressed miRNAs (miR-126–3p, miR-146a-5p, miR-20b-5p, miR-106a-5p, and miR-18a-3p). The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that their target functions included axon guidance, mitogen-activated protein kinase (MAPK) signaling, endocytosis, circadian rhythms, and cancer pathways. Expression profile of these miRNAs linked with menstrual cycle, antral follicle count, hormone level, and in combination, they produced a ROC curve area of 0.781 in differentiating PCOS patients from the controls. Findings overall suggest that differential expression of plasma exosomal miRNAs may confer a risk of PCOS and may allow differentiation of PCOS patients from controls.