In addition, studies have shown that PTGS2 increases the risk of pain in women with EMs (71), and the cyclooxygenase II (COX-2) enzyme, encoded by the PTGS2 gene, is naturally induced by aromatase and is involved in the conversion of arachidonic acid to prostaglandins, which may induce dysmenorrhea (26). Here, PTGS2 is linked to eosinophilia-myalgia syndrome.