Cause of Ectodermal Dysplasia:
Ectodermal Dysplasia is caused by a single abnormal gene or pair of abnormal genes. The chance for parents to have an affected child depends on the type of Ectodermal Dysplasia that exists in the family. In some families the mistake in the gene was a fresh mistake (mutation) in their child and the likelihood of another child being affected is very low. There are other families however that have an inherited form of Ectodermal Dysplasia with recurrence risk ranging from 25% to 50%.
Diminished or absent sweating is a common problem. The sweat glands are absent, reduced in number, or may not function normally. Reduced sweating may result in very high fevers, because the body regulates its temperature by sweating. Often, the first clue that the sweat glands are absent or are not functioning normally is an elevated temperature.
Elevations in body temperature are often caused by high environmental temperatures, excessive activity, or heavy clothing. When the body temperature is elevated, the skin feels dry, hot and may be flushed or pale.
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The scalp hair is absent, sparse, fine, lightly pigmented, or abnormal in texture. The hair may also be fragile and unruly, sticking out in all directions and difficult to comb. The hair is dry because the oil glands are absent or poorly developed.
Some defects of the hair are evident at birth, while others are not noted until later in life. Hair growth is slow and haircuts are not often needed. After puberty hair growth improves in some persons.
The eyebrows, eyelashes, and other body hair may also be absent or sparse, but beard growth in males is usually normal.
Most people with Ectodermal Dysplasia do not have nail abnormalities, although the nails are frequently dry and rough. A distinctive finding in one of the forms of Ectodermal Dysplasia is a short nail that fails to grow to the end of the finger. In others, the nails may be thin and fragile, thick and distorted, or brittle and slow- growing. Nails with any of the listed abnormalities may be prone to infection.
The teeth are missing altogether or reduced in number. Teeth that are present are widely spaced, tapered, or malformed. In persons with some types of Ectodermal Dysplasia, the enamel (outer layer of the teeth) is defective and there may be an excessive number of cavities. When teeth are missing the jawbones in which they are ordinarily embedded do not develop well, leading to a typical aged appearance in the face.
Ear, Nose, Throat:
The generalized underproduction of body fluids leads to several problems. Saliva is sparse, causing problems with chewing, tasting, and swallowing foods. The mucous secretions of the nose are excessively thick, forming a crusty mass. Nasal infections are common. A hoarse, raspy voice is common. Abnormal ear wax production may be noticed in some people with Ectodermal Dysplasia. The most frequent problem is accumulation of wax in the ear canal. Hearing loss may occur secondary to impacted wax or to nerve degeneration.
Tears are reduced, causing irritation of the eyes, conjunctivitis, and sensitivity to sunlight. There may be cloudy corneas or cataracts.
The linings of the nose, larynx, trachea and lungs are moistened by various glands, some of which may be defective in Ectodermal Dysplasia. Respiratory problems are therefore common.
Other sources of information about Ectodermal Dysplasia —
National Foundation of Ectodermal Dysplasias — https://www.nfed.org/