Keratin, type I cytoskeletal 13 (cytokeratin-13) is a type I cytokeratin. Cytokeratin 1 is paired with keratin 4 and found in the suprabasal layers of non-cornified stratified epithelia. Mutations in the gene encoding cytokeratin-13 and keratin 4 have been associated with the autosomal dominant disorder White Sponge Nevus (WSN). WSN is a rare autosomal dominant disorder which predominantly affects non-cornified stratified squamous epithelia. Clinically, WSN is characterized by the presence of soft, white, and spongy plaques in the oral mucosa.