Familial dysautonomia

A genetic disorder affecting the autonomic nervous system

Familial dysautonomia (FD), also known as Riley-Day syndrome, is a rare genetic disorder that affects the development and function of the autonomic nervous system and sensory nervous system. It is classified as a type of hereditary sensory and autonomic neuropathy (HSAN).

Genetics

Familial dysautonomia is an autosomal recessive disorder, meaning that an individual must inherit two copies of the defective gene, one from each parent, to be affected. The disorder is caused by mutations in the IKBKAP gene, which is located on chromosome 9. This gene is responsible for producing a protein called IKAP, which is involved in the development and maintenance of nerve cells.

Symptoms

The symptoms of familial dysautonomia are varied and can affect multiple systems of the body. Common symptoms include:

• Poor muscle tone (hypotonia)
• Feeding difficulties
• Lack of tears (alacrima)
• Frequent lung infections
• Difficulty regulating body temperature
• Episodes of dysautonomic crisis, characterized by vomiting, sweating, and changes in blood pressure and heart rate
• Scoliosis
• Poor growth and delayed development

Diagnosis

Diagnosis of familial dysautonomia is typically based on clinical evaluation and genetic testing. A blood test can identify mutations in the IKBKAP gene, confirming the diagnosis. Prenatal testing is also available for families with a known history of the disorder.

Management

There is no cure for familial dysautonomia, but treatment focuses on managing symptoms and improving quality of life. Management strategies may include:

• Nutritional support, such as feeding tubes
• Medications to control blood pressure and heart rate
• Physical therapy to improve muscle tone and coordination
• Regular monitoring and treatment of lung infections
• Surgery to correct scoliosis or other skeletal abnormalities

Prognosis

The prognosis for individuals with familial dysautonomia varies. Advances in medical care have improved life expectancy and quality of life for many patients. However, the disorder remains serious and can lead to complications that affect daily living.

Epidemiology

Familial dysautonomia is most commonly found in individuals of Ashkenazi Jewish descent, with a carrier frequency of approximately 1 in 30 in this population. It is much rarer in other ethnic groups.

Related pages

• Autonomic nervous system
• Hereditary sensory and autonomic neuropathy
• Genetic disorders
• Ashkenazi Jews