There are many different types of ectodermal dysplasia of which X-linked anhidrotic ectodermal dysplasia is the most common. Because the disease is X-linked, males are affected, although females in some cases may also display a range of symptoms.

An autosomal dominant form exists in which females and males are equally affected and is symptomatically almost identical to the X-linked form of the disease. Multiple genes have been discovered to cause ectodermal dysplasias.

Ectodermal dysplasia may affect, to varying degrees, all of the structures associated with the development of the skin. Absent or decreased sweating in people with anhidrotic ectodermal dysplasia is caused by absence of sweat glands.

Affected children have difficulty controlling fevers and mild illness may produce extremely high fevers, because of absent temperature regulation by sweating. Affected adults are unable to tolerate a warm environment and require special measures to maintain a normal body temperature.

Mucus membrane involvement results in chronic nasal infections with foul-smelling discharge and increased respiratory infections. Hair may be absent or very scanty. The skin is thin with light pigmentation. Teeth develop abnormally and many teeth are missing.

• decreased number of teeth
• peg teeth
• delayed or absent tooth formation
• inability to sweat
• absent tears (occasional)
• thin skin
• decreased pigment
• foul-smelling nasal discharge
• poor temperature regulation
• heat intolerance
• scanty hair
• absent hair
• abnormal nails
• low nasal bridge

• biopsy of the mucus membranes (shows absent mucous glands, hypoplastic mucous membranes)
• biopsy of the skin (shows absent or hypoplastic sweat glands)
• genetic testing is available for some subtypes of this group of disorders.

There is no specific treatment for this disorder. Cosmetic and functional improvements can be made through the use of wigs in the absence of scalp hair and dentures to replace missing and defective teeth. Synthetic tears may be necessary to replace normal tearing and prevent drying of the eyes. The nose may have to be irrigated frequently to remove purulent debris and prevent infection.

Temperature control is a constant problem. Affected people require a cooler climate and may require frequent cooling water baths or sprays to maintain a normal body temperature. (Water evaporating from the skin replaces the cooling function of sweat evaporating from the skin.)

• febrile seizures
• brain damage secondary to increased body temperature