Mal de Meleda (MDM) is a rare autosomal recessive skin disorder characterized by transgressive palmoplantar keratoderma (PPK), keratotic skin lesions, perioral erythema, brachydactyly, and nail abnormalities (summary by Fischer et al., 2001). The PPK in MDM is often accompanied by hyperhidrosis, maceration, fetid odor, and painful fissures (Ward et al., 2003). Some patients exhibiting similar but less severe features of MDM, with milder hyperkeratosis and no nail dystrophy, lichenoid plaques, pachydermia, or distant keratosis, were previously designated as having 'Gamborg Nielsen (Norrbotten) PPK' (see NOMENCLATURE).

Acrodermatitis enteropathica of the zinc deficiency type (AEZ) is characterized by intermittent simultaneous occurrence of diarrhea and dermatitis with failure to thrive. Alopecia of the scalp, eyebrows, and eyelashes is a usual feature. The skin lesions are bullous. Noteworthy is the cure by diodoquin, or diiodohydroxyquinoline (Dillaha et al., 1953; Bloom and Sobel, 1955). Rodin and Goldman (1969) described autopsy findings, including pancreatic islet hyperplasia, absence of the thymus and of germinal centers, and plasmocytosis of lymph nodes and spleen.

Any neonatal inflammatory skin and bowel disease in which the cause of the disease is a mutation in the ADAM17 gene.

Follicular ichthyosis, atrichia, and photophobia syndrome-2 (IFAP2) is characterized by ichthyosis follicularis or follicular hyperkeratosis, sparse to no body hair, and photophobia with corneal lesions. Ultrastructural hair analysis shows trichorrhexis nodosa (Wang et al., 2020). For a discussion of genetic heterogeneity of IFAP syndrome, see IFAP1 (308205).