MSH2 and pachyonychia congenita: For PC patients, DNA repair genes of interest include: HRR genes (most significant: BRAC2, BRCA1, ATM; others: ATR, BARD1, BRIP1, CHEK1, CHEK2, FAM175A, GEN1, MRE11A, PALB2, PPP2R2A, NBN, RAD31, RAD51B, RAD51C, RAD51D and RAD54L); MMR genes (MSH2, MSH6); Fanconi anemia genes (FANCA, FANCL); and CDK12 (3–5, 60).