KRT1 and palmoplantar keratoderma, epidermolytic: Homozygous nonsense mutations in KRT1 [e.g., c.457C>T (p. Gln153) and c.33C>G (p. Tyr11)] can lead to nonsense-mediated mRNA decay and KRT1 protein deficiency, resulting in epidermolytic palmoplantar keratoderma (EPPK) with knuckle pads (13); additionally, KRT1 mutations have been confirmed to cause epidermolytic hyperkeratosis, manifesting as ichthyosis-like hyperkeratosis (14).