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Prevalence is not known. The incidence is approximately 1/250,000 live male births for the X-linked form. Fewer than 10 patients with the autosomal-dominant form have been reported.

The clinical picture is variable. Typical signs of HED may be observed, such as sparse hair (atrichosis/ hypotrichosis), abnormal (e.g. conical) or missing teeth (anodontia/ hypodontia), decreased or absent sudation due to a lack of sweat glands (anhidrosis/ hypohidrosis), and typical facial features (protruding forehead, wrinkles under the eyes, characteristic periorbital hyperpigmentation) which are associated with immunologic defects such as susceptibility to opportunistic infections, hypogammaglobulinemia, impaired antibody response to polysaccharides or impaired NK-cell activity. Many patients fail to thrive. Ectodermal dysplasia-related symptoms of HED-ID, however, tend to be milder than in patients with other forms of HED. The disease can also be associated with osteopetrosis and lymphedema (hypohidrotic ectodermal dysplasia with immunodeficiency, osteopetrosis, lymphedema; see this term).

HED-ID is caused by hypomorphic mutations in the coding region of the IKBKG (or NEMO) gene (Xq28) or, less often, mutations in the NFKBIA gene (14q13), both involved in NF-κB activation.

Transmission is X-linked recessive in case of IKBKG mutations and autosomal-dominant in case of NFKBIA mutations. Somatic mosaicism seems to occur frequently in HED-ID patients.