The ectodermal dysplasias are a group of inherited disorders that involve defects in the hair, nails, sweat glands and teeth. At least two types of abnormal ectodermal features—for example, malformed teeth and extremely sparse hair— must exist to coin the diagnosis of ectodermal dysplasia.
All ectodermal dysplasias possess a genetic basis and 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.
The ectoderm is the outermost layer of cells in embryonic development and is involved in the formation of many body tissues. Failure of the ectoderm to develop normally results in ectodermal dysplasias. Please note that this is mostly a congenital disease (present since birth) and is non-progressive; at times however, it is not suspected until teeth fail to develop normally.
To date, about 150 different types of ectodermal dysplasias have been identified. Subgroups are differentiated according to the presence or absence of the four primary ectodermal dysplasia (ED) defects:
ED1: Trichodysplasia (hair dysplasia)
ED2: Dental dysplasia
ED3: Onychodysplasia (nail dysplasia)
ED4: Dyshidrosis (sweat gland dysplasia)
The genetic mutation responsible for the disease cannot be isolated in all types; specific genetics tests to diagnose ectodermal dysplasia are available for only a limited number of ectodermal dysplasias.
The derivatives of the ectoderm that get affected include:
Teeth may be missing, pointed, widely spaced, or prone to cavities because of defective enamel. Children may require dentures in early childhood, and dental implants may be needed in adolescence.
Scalp and body hair may be absent, sparse, thin, very light in color, excessively brittle, curly, or even twisted.
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 because their sweat glands may function abnormally or may not even exist in the first place. This results in an inability to regulate body 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..
Dryness of the eye, sensitivity to sunlight, cataracts, vision defects, hearing problems, respiratory infections, cleft lip and/or palate, lack of breast development, or missing fingers and toes.
There is no specific treatment for ectodermal dysplasia. The condition is managed by treating the various symptoms.