Familial Dysautonomia

What is familial dysautonomia?

Familial dysautonomia is a genetic disorder that affects the development and survival of certain nerve cells. The disorder disturbs cells in the autonomic nervous system, which controls involuntary actions such as digestion, breathing, production of tears, and the regulation of blood pressure and body temperature. It also affects the sensory nervous system, which controls activities related to the senses, such as taste and the perception of pain, heat, and cold. Familial dysautonomia is also called hereditary sensory and autonomic neuropathy, type III.

Problems related to this disorder first appear during infancy. Early signs and symptoms include poor muscle tone (hypotonia), feeding difficulties, lack of tears, and difficulty maintaining body temperature. Developmental milestones, such as walking and speech, are usually delayed. Characteristic symptoms in older children and adults include poor balance, curvature of the spine (scoliosis), episodes of vomiting, frequent lung infections, reduced sensitivity to pain and temperature changes, abnormal sense of taste, poor regulation of blood pressure, and heart problems.

How common is familial dysautonomia?

In populations of individuals with Central or Eastern European (Ashkenazi) Jewish ancestry, familial dysautonomia occurs in about 1 in 3,700 people. This disorder is rare in the general population.

What genes are related to familial dysautonomia?

Mutations in the IKBKAP gene cause familial dysautonomia.

Nearly all individuals with familial dysautonomia have two copies of the same mutation in each cell, which causes part of the IKBKAP gene to be skipped when it is copied for production of the IKAP protein. This skipping mutation results in a decreased amount of IKAP protein in their cells. This mutation, however, behaves inconsistently. As a result, some cells produce near normal amounts of IKAP protein, and other cells—particularly nerve cells—have very little IKAP protein. Critical activities in nerve cells are probably disrupted by reduced amounts or the absence of IKAP protein, leading to the signs and symptoms of familial dysautonomia.

How do people inherit familial dysautonomia?

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

What other names do people use for familial dysautonomia?

• FD
• HSAN3
• HSAN Type III
• HSN-III
• Riley-Day Syndrome