epidermal disease ichthyosis (disease) DOID:1697 Disorders of cornification that are characterized by visible scaling and/or hyperkeratosis of most or all of the skin. Inherited ichthyoses, defined as the generalized form of Mendelian disorders of cornification, affect most or all of the skin. This etiologically and phenotypically heterogenous group of conditions is caused by mutations in various different genes important for keratinocyte differentiation and epidermal barrier function. Acquired forms of ichthyosis can be observed with certain autoimmune, inflammatory, metabolic, endocrine, or infectious diseases or with malignancies. Epidermal keratinocytes undergo a unique form of terminal differentiation and programmed cell death known as cornification. Cornification leads to the formation of the outermost skin barrier, i.e. the cornified layer, as well as to the formation of hair and nails. HP:0008064 MESH:D007057 MONDO:0019269 MedDRA:10021198 NCIT:C84776 Orphanet:79354 UMLS:C0020757 fish scale disease fish skin disease https://github.com/monarch-initiative/mondo/pull/2110 ichthyoses ichthyosis non-syndromic ichthyosis