Mutations in MBTPS2 have been reported to cause a broad phenotypic spectrum of X-linked genodermatoses, including IFAP (ichthyosis follicularis; atrichia and photophobia) syndrome (OMIM 308205) with or without BRESHECK (brain anomalies, retardation of mentality and growth, ectodermal dysplasia, skeletal malformations, Hirschsprung disease, ear deformity and deafness, eye hypoplasia, cleft palate, cryptorchidism, and kidney dysplasia/hypoplasia) syndrome, keratosis follicularis spinulosa decalvans (KFSD; OMIM 308800) and an X-linked form of Olmsted syndrome.