Hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) is a rare genetic disorder that primarily affects the development of the skin, hair, nails, teeth, and sweat glands. It is one of the many types of ectodermal dysplasia.

Signs and Symptoms

Individuals with HED typically exhibit the following characteristics:

• **Hypohidrosis**: Reduced ability to sweat due to underdeveloped or absent sweat glands, leading to difficulty in regulating body temperature.
• **Hypotrichosis**: Sparse, thin, and light-colored hair on the scalp and body.
• **Dental abnormalities**: Missing teeth (hypodontia) or teeth that are pointed or cone-shaped.
• **Facial features**: Distinctive facial features including a prominent forehead, thin lips, and a flattened bridge of the nose.
• **Skin**: Dry, thin skin that may be prone to eczema or infections.

Genetics

HED is most commonly inherited in an X-linked recessive pattern, which means the gene responsible for the condition is located on the X chromosome. Males are more frequently affected because they have only one X chromosome. Females with one affected X chromosome are typically carriers and may exhibit milder symptoms. The condition can also be inherited in an autosomal recessive or autosomal dominant manner, though these forms are less common.

Diagnosis

Diagnosis of HED is based on clinical evaluation, family history, and genetic testing. The characteristic features of the disorder often lead to a clinical diagnosis, which can be confirmed by identifying mutations in the EDA, EDAR, or EDARADD genes.

Management

There is no cure for HED, but management focuses on alleviating symptoms and improving quality of life. This may include:

• **Temperature regulation**: Measures to prevent overheating, such as air conditioning, cooling vests, and frequent hydration.
• **Dental care**: Use of dentures, dental implants, or other dental prosthetics to address missing or abnormal teeth.
• **Skin care**: Moisturizers and other treatments to manage dry skin and prevent infections.
• **Genetic counseling**: For affected individuals and their families to understand the inheritance pattern and risks for future offspring.

Epidemiology

HED is a rare condition, with an estimated prevalence of 1 in 10,000 to 1 in 100,000 live births. It affects individuals of all ethnic backgrounds.

See Also

• Ectodermal dysplasia
• X-linked recessive inheritance
• Genetic disorder