Novel and recurrent mutations in keratin 1 cause epidermolytic ichthyosis and palmoplantar keratoderma.

Mutations in keratin genes underlie a variety of epidermal and nonepidermal cell-fragility disorders, and are the genetic basis of many inherited palmoplantar keratodermas (PPKs). Epidermolytic PPK (EPPK) is an autosomal dominant disorder that can be due to mutations in the keratin 1 gene, KRT1. Epidermolytic ichthyosis (EI), the major keratinopathic ichthyosis, is characterized by congenital erythroderma, blistering and erosions of the skin. Causative mutations in KRT1 and KRT10 have been described, with PPK being present primarily in association with the former. We report four unrelated cases (one with sporadic EI and three with autosomal dominant PPK), due to two novel and two recurrent KRT1 mutations. Mutations in KRT1 are not only scattered throughout the keratin 1 protein, as opposed to being clustered, but can result in a range of phenotypes as further confirmed by these mutations, giving a complex genotype/phenotype pattern.