BRCA1 and pachyonychia congenita: Consensus clinical genetic testing guidelines include PC as a component tumor for seven of the confirmed PC genes in this study (BRCA1/2, MSH2, MSH6, ATM, PALB2, and CDKN2A).27, -29 Clinical histories of patients with mutations in these genes were evaluated to determine whether the respective genetic testing criteria were met (Table 5).