CFTR and pachyonychia congenita: Variants of cystic fibrosis transmembrane conductance regulator (CFTR) [87], serine protease inhibitor Kazal type 1 (SPINK1), and cationic trypsinogen (PRSS1) [88] develop PC during long-standing chronic pancreatitis, so that PC can be accompanied by severe pancreatic atrophy, pancreatic stones, and duct ectasia.