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What

Hidrotic Ectodermal Dysplasia (HED) is a rare genetic condition that is present in children at birth, but symptoms may not be recognized during the newborn period (first 28 days of life). The most common symptom is thick, slow growing and brittle fingernails and toenails which is the only symptom in one third of the families affected by this disease. Another common symptom is thin and sparse scalp hair and thin or absent eyebrows and eyelashes. Thick skin over the palms of the hands, soles of the feet, knuckles, knees, and elbows is also common.

Who

Originally, most people who were diagnosed with HED were of French descent that then migrated to places like Canada, Scotland and the northern United States. This disease has now been diagnosed in people from a variety of places around the world including China, England, Spain, Africa, and Malaysia. HED has been reported most often in Caucasians, but has also been described in people of other races. Males and females are equally affected. The prevalence of HED in the general population is currently unknown.

Signs and Symptoms

Hidrotic Ectodermal Dysplasia may affect each individual differently, but commonly signs and symptoms include: • Thick and discolored nails which are apparent early in infancy. The nails will be slow growing and brittle. Persistent fungal infections of the nail (onychomycosis) are common and may cause roughness and splitting of the nail. Infections of the skin around the base of the nail are also common and may be due to fungi or bacteria (most commonly due to Streptococci or Staphylococci bacteria). • Scalp hair is usually sparse and brittle with pale color. Eyebrows and eyelashes may be thin or absent. Body hair is also sparse. Hair loss may be progressive and loss of all the hair on the body (total alopecia) can occur eventually. • The skin may be very thick on the palms of the hands and the soles of the feet. There may also be thickening and darkening (hyperpigmentation) of the skin over the knuckles, knees, and elbows. • Less commonly, children may have eye problems, such as crossed eyes, premature cataracts, and conjunctivitis (inflammation of the lining of the eye and eyelids). • It is also possible, though not common, for children to have hearing loss, learning problems, extra fingers or toes, or webbing of some fingers or toes. • Children with HED have a normal ability to sweat and have normal teeth (inability to sweat and abnormal teeth are found in other forms of ectodermal dysplasia).

Possible Causes

Hidrotic Ectodermal Dysplasia is a genetic disease caused by a change (mutation) in a gene named GJB6, which is located on chromosome 13. Early on in development, three layers of cells develop which will eventually form the specific tissues and organs of the body. These three layers are called the ectoderm, mesoderm and endoderm. In HED, a genetic change in the GJB6 gene causes a variety of abnormalities to occur in the ectoderm, which results in the signs and symptoms described above. This disorder is inherited in an autosomal dominant manner. This means that if either parent has one copy of the GJB6 gene with a change and passes this gene on to their child, then the child will also develop this disorder.

Diagnosis

Diagnosis is usually confirmed by physical examination and a full history to determine which symptoms are present and if any other family members have similar symptoms. Abnormalities of the nails and skin, in addition to the hair loss will suggest HED. A variety of tests may be done to rule out other forms of ectodermal dysplasia. Tests can be done to determine if the child can sweat properly. Children with HED would have a normal test, while children with other forms of ectodermal dysplasia would not sweat or may only sweat minimally. A sample of hair may be analyzed to determine if it is brittle. A genetic test can be done to determine if the child has a mutation in the GJB6 gene.

Treatment

Certain medications can be used to help decrease the thickening of the skin on the palms of the hands and the soles of the feet. Lubrication of the eyes and control of the fungal and bacterial infections of the nail and skin around the nail are important. Many people choose to wear wigs to compensate for the thin, sparse and brittle scalp hair. There is currently no cure for HED, but research is ongoing in the hope of reaching this ultimate goal.

Prognosis

The prognosis for most children with Hidrotic Ectodermal Dysplasia is generally good. With proper treatment and control of bacterial and fungal infections most children with HED are able to live normal and happy lives without any limits in activities.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

National Foundation for Ectodermal Dysplasias
This is a great website with general information about ectodermal dysplasias, links to information about current research, and links to information about support.

Ectodermal Dysplasia Society
This website has links with support and advice, general information about ectodermal dysplasia, and links to articles about ectodermal dysplasia.

EMedicine: Ectodermal Dysplasia
This website has detailed and technical information about Hidrotic Ectodermal Dysplasia and other ectodermal dysplasias.

Google Search for Hidrotic Ectodermal Dysplasia (HED)

References and Sources

OMIM www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=129500 EMedicine: Ectodermal Dysplasia www.emedicine.com/derm/topic114.htm Schachner LA, Hansen RC (2003). Pediatric Dermatology. 3rd ed. Missouri: Mosby, Inc., Weston WL, Lane AT, Morelli JG (2002). Color Textbook of Pediatric Dermatology. 3rd ed. Missouri: Mosby, Inc.