Definition:

Ectodermal dysplasia (ED) refers to a group of inherited disorders involving absence or dysplasia of the ectodermal appendages. Clinically, it is characterized by absence, abnormality, or deficient function of ectodermal derivatives, including skin, teeth, hair, eccrine glands, or nails. In the hypohidrotic/ anhidrotic form of ED (HED/EDA) the patient has no sweat glands, sparse scalp hair and rare conical teeth. Patients with EDA and immunodeficiency (EDA-ID) present some or all of these features, together with severe infectious diseases. EDA-ID principally affects boys, suggesting X-linked recessive inheritance (XL-EDA-ID). This was confirmed in 2000 and beyond with the identification of disease-causing hypomorphic mutations in NEMO, which is located on the X chromosome and encodes IKK-gamma. A novel autosomal dominant of EDA-ID, recently identified in one child, was found to be caused by a hypermorphic mutation of the gene encoding I{kappa}B{alpha}. Similar to XL-EDA-ID patients, from the age of two months he suffered from multiple and severe infections with several Gram-positive and Gram-negative bacteria, leading to chronic bronchopneumonitis and gastroenteritis, with failure to thrive.