SERPING1 and endometriosis: Additionally, researchers observed significantly elevated levels of C1q, mannose-binding lectin (MBL), and C1 inhibitor (C1INH) in the peritoneal fluid (PF) of women with endometriosis compared to healthy controls (p < 0.0001), with these differences being particularly pronounced during the early stages of the disease (Sikora et al., 2018).