Histidinemia is a rare hereditary metabolic disorder characterized by a deficiency of the enzyme histidase, which is necessary for the metabolism of the amino acid histidine. The concentration of histidine is elevated in the blood. Excessive amoun...

Netherton syndrome is a rare hereditary disorder characterized by scaling skin, hair anomalies, increased susceptibility to atopic eczema (a skin condition that can result in dry, red and flaky skin), elevated IgE levels, and other related symptom...