SGMS2 and pachyonychia congenita: Serum levels of CA19-9 were higher in patients with PC (303.1 [69.2–593.5] U/mL) than in all controls (HC, 15.1 [8.4–25.2] U/mL; BC, 11.6 [8.8–34.6] U/mL; CDL, 48.5 [27.6–61.4] U/mL; CP, 35.6 [27.4–44.7] U/mL), as shown in Fig. 1b.