Ectodermal dysplasia (ED) is a hereditary condition characterized by abnormal development of the skin and associated structures (hair, nails and teeth, and sweat glands). Each person with ectodermal dysplasia may have a different combination of defects. One may have hair and nails affected, while another may have involvement of sweat glands and
teeth. Each combination is considered a distinct type of ectodermal dysplasia.
There are many disorders that involve one of these structures only and are not properly called ED. Any combination of defects involving more than one of these structures, however, should be called an Ectodermal Dysplasia Syndrome; the list of such combinations is extensive. For example, one person may have missing teeth and defective nails, while another may have missing teeth, inability to sweat, and sparse hair. Still another may have sparse hair and a hearing loss. Each combination of features represents another type of ED Syndrome and has a specific name.
Ectodermal dysplasias are caused by altered genes. The altered genes may be inherited or normal genes may become defective (mutate) at the time of conception. The chances for parents to have affected children depend on the type of ED that exists in the family. It is important to remember that a person cannot choose or modify the genes that he or she has, and that events of pregnancy do not change the genes. Thus, parents who have a child with ED should not think that they did anything to cause the defective gene and should not blame themselves for its existence. Genetic counselling is available for families.
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.
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.)
Anhidrotic ectodermal dysplasia is a sex linked recessive condition that manifests fully in affected males and partially in females. It’s association with atrophic rhinitis has been reported earlier even in infancy. The classical triad of anhidrotic ectodermal dysplasia consists of hypotrichosis, anodontia and anhidrosis. Ninety per cent of the affected patients are male. Absent or reduced sweating is a prominent feature. Biopsy confirms that eccrine glands are absent or rudimentary and this may be used as a basis for prenatal diagnosis. The facial features and apearance of these patients are conspicuous. Hypo-trichosis is generalized but incomplete with scraggly, thin, sparse, blond and dry hair. There is usually partial or total anodontia. Nails may be thin, brittle and ridged. The skin is soft, thin, dry and smooth. Mental retardation is present in some cases possibly as a consequence of hyperthermic episodes of childhood. The complete syndrome does not occur in females but carriers may show varying degree of dental defects, sparse hair, reduced sweating and dermatoglyphic abnormalities.
Though the general appearance of the patient of anhidrotic ectodermal dysplasia is typical and hard to miss, it has to be differentiated from conditions like syphilis, leprosy which may present as secondary atrophic rhinitis with all its classical features of episatxix and not uncommonly maggots inside the nasal cavity. The local nasal condition has no permanent cure and nasal douching cures only the local nasal symptoms. The depressed nasal bridge occurs due to the compromised blood supply to the growing nasal and septal bones as a result of severe inflammatory reaction.