What is Ectodermal Dysplasia?|Causes, Classification, Symptoms, and Treatment of Ectodermal Dysplasia

Ectodermal dysplasia is a broad term used to describe a rare group of genetic or inherited disorders characterized by defects in hair, nails, and teeth or in the function of sweat glands.^{(1, 2, 3)} There also can be problems with organs having any tissue originating from ectoderm, such as eyes, ears, lips, mucous membranes of the nose or mouth and the central nervous system.⁽²⁾

The outermost cell layer present during the development of the embryo is the ectoderm and this contributes to the development of many body parts, such as mentioned above.

The cause of ectodermal dysplasia is abnormal development of the ectoderm in some areas.  Every case of ectodermal dysplasia is congenital and is non-progressive.

The cause of development of different forms of ectodermal dysplasia is the deletion or mutation of specific genes present on various chromosomes.⁽¹⁾ As ectodermal dysplasias occur due to a genetic defect, these syndromes are inherited or passed from families. If ectodermal dysplasia occurs in people who do not have a family history of this condition, then it has occurred due to a De Novo mutation.

As of now, there are around 150 different forms of ectodermal dysplasias. Subgroups are created to better understand and this classification was made depending on absence or presence of the four primary defects of ectodermal dysplasia: (ED)⁽¹⁾

• ED1: Trichodysplasia (hair dysplasia).
• ED2: Dental dysplasia.
• ED3: Onychodysplasia (nail dysplasia).
• ED4: Dyshidrosis (sweat gland dysplasia).

According to the above there are 150 different types of ectodermal dysplasias grouped into different subgroups, which were formed according to the primary defects of ectodermal dysplasia.

Hypohidrotic (anhidrotic) is the commonest ectodermal dysplasia, which comes under the subgroup 1-2-3-4 and hidrotic ectodermal dysplasia falls under the subgroup 1-2-3.

The three most distinguished ectodermal dysplasia syndromes are in the subgroup 1-2-3-4, because they exhibit characteristics from all four of the main ectodermal dysplasia defects and these are:⁽¹⁾

• Ectrodactyly-ED-clefting syndrome.
• Rapp-Hodgkin hypohidrotic ectodermal dysplasia.
• Ankyloblepharon, ectodermal defects, Hay-Wells syndrome or cleft lip/palate (AEC).

The symptoms of ectodermal dysplasia can be markedly different among the different types and occurs according to the affected structures. The signs and symptoms of ectodermal dysplasia are often not obvious in newborns and can remain undetected till infancy or even childhood.

The four organs primarily affected by ectodermal dysplasia with the following symptoms are:^{(1, 2, 3)}

• Hair: The hair present on the scalp and body will be sparse, thin and light in color. The hair can also be excessively brittle, coarse, curly or twisted.
• Nails: The fingernails and toenails will be thick, with an abnormal shape, ridged, brittle, slow-growing and have discoloration. In some cases, nails can be absent altogether. The cuticles can be susceptible to infection too.
• Teeth: There is abnormal development of tooth causing missing teeth or abnormal shaped teeth, which are pointed or peg-shaped.⁽¹⁾ The enamel of the teeth is also defective. Treatment with a dentist is a must and young children can also require dentures.
• Sweat Glands: The eccrine sweat glands can be few or completely absent, so there is zero functioning of the sweat glands or abnormal function of the sweat glands. Without normal production of sweat, the body is not able to properly regulate its temperature. Due to this, children can have recurrent high fever, which can result in seizures and neurological problems. A common problem is overheating more so for patients living in warmer climates.

Some of the other signs and symptoms of ectodermal dysplasia are:^{(1, 2, 3)}

• The patient can have lightly pigmented skin and can also have brown or red pigment present.
• The skin over the soles and palms can be thick and susceptible to cracking, bleeding and infection.
• There can be dryness of the skin which can easily develop rashes and infection.
• Hearing problems can occur due to abnormal development of the ear.
• Due to lack of tears, the patient will have dry eyes and can also suffer from visual defects and cataracts.
• There can be development of cleft palate/lip.
• The patient can have missing fingers or toes.
• There is bad-smelling nasal discharge caused by chronic nasal infections.
• Respiratory infections occur easily because of the absence of the protective secretions from the nose and mouth.
• There also can be lack of breast development.

Ectodermal dysplasia has no specific treatment and management of this condition is done by symptomatic treatment. Treatment of ectodermal dysplasia needs a team of dentists and other specializing doctors.

Artificial tears are prescribed to patients having defective tear production to prevent corneal damage. Saline sprays are also helpful.

Patients with no sweat gland function or abnormal sweat gland function are better off living in cooler climates or should have air conditioning at school, home and work place. Patients can also benefit from cool water sprays and baths; and drink water and other fluids frequently to maintain the normal temperature of the body.⁽²⁾

• Doing saline irrigation of the mucosa of the nose helps in removing the pus and other debris present in the nose and prevents infection.
• It is important to have dental evaluation and intervention as early as possible.
• If the patient has little to no hair and is conscious of his/ her appearance, then wigs can be worn.
• Surgery to repair cleft palate helps in improving speech and reducing the deformities of the face.

Once patients understand how to manage their condition, majority of them suffering from ectodermal dysplasia can have a full and productive life. Children suffering from mucus and sweat production abnormalities need extra attention. Recurrent high fevers should be not be ignored, as if left untreated they can cause neurological problems and seizures.

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