Ectodermal dysplasia is a group of conditions in which there is abnormal development of the skin, hair, nails, teeth, and sweat glands.

There are many different types of ectodermal dysplasia.

Many gene defects cause ectodermal dysplasias. The most common form of ectodermal dysplasia is linked to the X chromosome and usually affects men. Other forms of the disease affect men and women equally.

Persons with ectodermal dysplasia may not sweat or have decreased sweating because of a lack of sweat glands.

Children with the disease may have difficulty controlling fevers. Mild illness can produce extremely high fevers, because the skin can't sweat and control temperature properly.

Affected adults are unable to tolerate a warm environment and need special measures to keep a normal body temperature.

Other symptoms include:

• Abnormal nails
• Abnormal and missing teeth
• Absent or very thin hair
• Absent tears (occasional)
• Decreased skin color (pigment)
• Foul-smelling nasal discharge
• Heat intolerance
• Inability to sweat
• Large forehead
• Light coloring
• Lower-than-normal number of teeth
• Low nasal bridge
• Poor temperature regulation
• Thin hair
• Thin skin

Tests that may be done include:

• Biopsy of the mucous membranes
• Biopsy of the skin
• Genetic testing (available for some types of this disorder)