A genetic skin disorder caused by mutations in the KRT9 gene. It is characterized by hyperkeratosis in the palms and soles resulting in abnormal thickening of the skin in these areas. The disease is Monarch Disease Ontology term MONDO_0007758 (epidermolytic palmoplantar keratoderma, 1). Also known as: EPPK, diffuse erythrodermic palmoplantar keratoderma, VC6rner type, diffuse erythrodermic palmoplantar keratoderma, Voerner type, epidermolytic palmoplantar keratoderma of VC6rner, epidermolytic palmoplantar keratoderma of Voerner.