Any hereditary mucosal leukokeratosis in which the cause of the disease is a mutation in the KRT4 gene. The disease is MONDO_0008676 (white sponge nevus 1). Also known as: KRT4 hereditary mucosal leukokeratosis, White sponge Nevus type 1, hereditary mucosal leukokeratosis caused by mutation in KRT4.