The ectodermal dysplasias are inherited disorders that involve defects in the hair, nails, sweat glands and teeth. When a person has at least two types of abnormal ectodermal features—for example, malformed teeth and extremely sparse hair—the individual is identified as being affected by ectodermal dysplasia.
The conditions are a remarkably diverse group of disorders which may also affect other parts of the body. The ectoderm contributes to the formation of the lens of the eye, parts of the inner ear, the fingers and toes, and nerves, among others. Therefore, ectodermal dysplasia may cause these parts of the body to develop abnormally.
There are more than 150 different types of ectodermal dysplasias. Symptoms range from mild to severe. Only in rare cases does ectodermal dysplasia affect lifespan and very few types involve learning difficulties.
In some cases, ectodermal dysplasia is apparent at birth. In other cases, a parent or doctor may only begin to suspect that a problem exists when teeth fail to develop normally. The ectodermal dysplasias are diagnosed by the pattern of what part of the body is affected and how it has developed and functions.
Specific genetics tests to diagnose ectodermal dysplasia are available for only a limited number of ectodermal dysplasias.
All ectodermal dysplasias are heritable or genetic disorders, which means that they can be inherited or passed on to children. However, it is possible for a child to be the first person in his or her family to be affected by an ectodermal dysplasia. In that case, the condition likely has been caused by a change in the DNA or a genetic mutation.
No one is really sure. The latest estimate, published in the 1990 edition of The Birth Defects Encyclopedia, is that as many as seven of every 10,000 babies are born affected by an ectodermal dysplasia.
Ectodermal dysplasias affect both males and females of all races and ethnic groups.
There are no cures for ectodermal dysplasias, but many treatments are available to address the symptoms. Research is ongoing to learn more about how different genes cause ectodermal dysplasias, what may be done to prevent the disorders in the future, and how to better treat individuals who are affected.
Teeth may be missing, pointed, widely spaced, or prone to cavities because of defective enamel. Dental treatment is almost always necessary and children may need dentures as early as two years of age. Multiple denture replacements are needed as the child grows, and dental implants may be an option in adolescence. Orthodontic treatment may also be necessary.
Scalp and body hair may be absent, sparse, thin, very light in color, excessively brittle, curly, or even twisted. Wigs can mask defects in hair development.
Fingernails and toenails may be thick or thin, abnormally shaped, discolored, ridged, slow-growing, or brittle. The cuticles may be prone to infections.
Many individuals affected by ectodermal dysplasia cannot perspire. Their sweat glands may function abnormally or may not have developed at all. Without normal sweat production, the body cannot regulate temperature properly. Therefore, overheating is a common problem, especially during hot weather. Access to cool environments is important.
Skin may be thin and pale, dry, scaly and easily irritated, prone to rashes, infections and sunburn, or thick over the palms and sole. Skin erosions or open areas of the skin on the scalp, hands and feet are possible. Care must be taken to prevent cracking, bleeding, and infection.
In some cases, problems occur with other parts of the body which also develop from the ectoderm: dryness of the eye, sensitivity to sunlight, cataracts, vision defects, hearing problems, respiratory infections, cleft lip and/or palate, or missing fingers and toes.