TGM1 and inherited ichthyosis: Among these genes are TGM1, CDSN, LOR, SPINK5, and FLG, each of whose mutation causes monogenic skin diseases characterized by abnormal epidermal barrier function, such as autosomal recessive congenital ichthyosis(44), peeling skin disease(45), keratoderma hereditaria mutilans(46), ichthyosis linearis circumflexa(47), and ichthyosis vulgaris(48) respectively.