Familial Dysautonomia

Inherited Nervous System Disorder

Familial dysautonomia (also known as Riley-Day syndrome) is an inherited genetic disorder that affects the autonomic and sensory nervous systems. This disorder occurs in about 1 in 3,700 individuals of Ashkenazi (Eastern European) Jewish ethnicity, and is very rare in people of other ethnic backgrounds.

Mutations in a gene known as IKBKAP cause familial dysautonomia. It is inherited as an autosomal recessive disorder, meaning that a child has to receive two copies of the defective gene -- one from each parent -- in order to develop the disorder. It is estimated that about 1 in 27 Ashkenazi Jews carries a form of the IKBKAP genetic mutation.

Dysautonomia

Dysautonomia is a term that means abnormal functioning of the autonomic nervous system. This part of the nervous system controls involuntary body functions such as digestion, breathing, production of tears, and regulation of blood pressure and body temperature. Many diseases, such as Parkinson’s disease, mitochondrial disorders, Shy-Drager syndrome, and multiple system atrophy can have dysautonomia as part of the disease.

Symptoms

The symptoms of familial dysautonomia result from the abnormal functioning of the autonomic and sensory nervous systems. The disease becomes worse over time, so some individuals may have mild symptoms while others have more severe symptoms. These symptoms may include:

• a lack of tears when crying, and dry eyes
• a decreased ability to feel pain, hot or cold
• swings in blood pressure and/or body temperature
• smooth tongue, which may appear shiny and lack taste buds
• trouble with feeding and swallowing
• poor muscle tone (hypotonia)
• heartburn (reflux), vomiting, constipation
• developmental delays
• red blotches on the skin that come and go
• excessive sweating
• sideways curvature of the spine (scoliosis)
• poor weight gain and growth
• holding the breath too long
• short stature

Diagnosis

The diagnosis of familial dysautonomia is based on the presence of these symptoms:

• Lack of tears when crying
• Smooth tongue
• Decreased deep tendon reflexes
• Abnormal response to an intradermal histamine test – The normal response to a histamine injection under the skin is to have a raised bump and redness. In familial dysautonomia a bump raises up but it looks different than it should.
• Both parents of Ashkenazi Jewish heritage

In addition, genetic testing can be done to look for the IKBKAP mutation. Over 99% of individuals with familial dysautonomia will have two copies of the most common mutation. Once a child is diagnosed with the disease, other family members can be tested to see if they carry the genetic mutation for it.

Treatment

Treatment of familial dysautonomia is focused on the symptoms that are present. Treatments include topical lubrication of the eyes, and medications to maintain and regulate blood pressure and reduce reflux. Surgery may be needed to correct scoliosis or reduce severe reflux. Physical, occupational, and speech therapies can help promote growth and development.

_Sources:

"About Familial Dysautonomia." United Jewish Communities. 20 Nov 2007

"FD Fact Sheet." 2006. Dysautonomia Foundation, Inc. 20 Nov 2007

"Familial dysautonomia." Genetic Conditions. May 2007. Genetics Home Reference. 20 Nov 2007

"About Familial Dysautonomia." 2001. FD Hope. 20 Nov 2007