KRT1 and epidermolytic palmoplantar keratoderma, 1: Significantly, homozygous nonsense mutations in KRT1 (c.457C>T, p. Gln153; c.33C>G, p. Tyr11) have been linked to epidermolytic palmoplantar keratoderma (EPPK) with knuckle pads, resulting from nonsense-mediated mRNA decay and loss of KRT1 protein (13).