SERPINC1 and Pelizeaus-Merzbacher spectrum disorder: The pathogenesis of PMD remains unclear, but several studies have found some risk factors of PMD: vacuum erection device, penile trauma, strong sexual activity, prolonged erection, prolonged sitting position, hypercoagulation, urogenital infection, hematological disease, prostate biopsy and deficiency of S and C proteins and antithrombin III (found in 15%–20% of all families with thrombophilia).11,12