ATM and pachyonychia congenita: The most frequent germline genetic alterations associated with PC are present in BRCA2, PALB2, ATM (ataxia telangiectasia) and CDKN2A/p16 (familial atypical multiple mole melanoma, FAMMM) and, less frequently, BRCA1, APC, MLH1, MSH2, MSH6, PMS2, PRSS1 (hereditary pancreatitis) and STK11 [17].