GGT5 and endometriosis: GGT5 was responsible for converting leukotriene C4 (LTC4) to leukotriene D4 (LTD4), both of which were found with an increment of concentration in menstrual blood from patients with primary dysmenorrhea (Rees et al., 1987) and the highly selective LTD4 receptor antagonist had an inhibiting effect on endometriotic implant growth in rat endometriosis model (Kiykac Altinbas et al., 2015).