Several germline variants have been suggested as relevant in PC such as those in ATM (ataxia-telangiectasia mutated), BRCA1 (breast cancer), BRCA2, MSH2 (MutS Homolog 2), MLH1 (mutL homolog 1), MSH6 (MutS Homolog 6), PMS2 (PMS1 homolog 2), EPCAM (epithelial cellular adhesion molecule) and HOXB13 (Homeobox B13) genes (Saunders et al., 2021). The gene discussed is MLH1; the disease is pachyonychia congenita.