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Familial Dysautonomia

Also known as: Riley-Day syndrome, HSAN Type III

Background

Familial dysautonomia (FD) is a genetic condition that affects the development and survival of certain nerve cells. It affects the nerves that are part of the autonomic nervous system, which control activities that our bodies carry out without us thinking about it, such as breathing, digestion, producing tears and controlling blood pressure. FD also affects the sensory nervous system and so people have difficulty sensing pain. It is part of a group of conditions known as hereditary and sensory autonomic neuropathy (HSAN) see entry Congenital Insensitivity/Indifference to Pain.

Credits

Medical text written January 2002 by Contact a Family. Approved January 2002 by Professor F Axelrod. Last updated December 2012 by Professor F Axelrod, Professor of Dysautonomia Treatment and Research and Professor of Neurology, New York University School of Medicine, New York, USA.

What are the symptoms?

Symptoms of FD include:

  • hypotonia (poor muscle tone)
  • feeding difficulties
  • poor growth
  • lack of tears
  • attacks of nausea with vomiting
  • frequent lung infections
  • difficulty maintaining body temperature
  • erratic swings in blood pressure.

Older infants and young children with FD may hold their breath for long periods of time, which may cause cyanosis (a bluish appearance of the skin or lips) or fainting. Developmental milestones, such as walking and speech, are usually delayed, although some affected individuals show no signs of developmental delay. Other problems include:

  • scoliosis (curvature of the spine)
  • poor bone quality and increased risk of bone fractures
  • kidney and heart problems.

About one-third of children with FD have learning disability. By adulthood, affected individuals often have increasing difficulties with balance and walking unaided.

Other problems that may appear in adolescence or early adulthood include lung damage due to repeated infections, impaired kidney function, and worsening vision due to the shrinking size (atrophy) of optic nerves, which carry information from the eyes to the brain.

'Dysautonomia crisis' is a group of symptoms that include nausea, high blood pressure, fast heart rate and a change in personality. It is usually caused by stress. Episodes can occur as frequently as daily, but some patients will never experience a crisis.

What are the causes?

Changes (mutations) in the IKBKAP gene cause FD. The IKBKAP gene provides instructions for making a protein called IKK complex-associated protein (IKAP). This protein is found in a variety of cells throughout the body, including brain cells. The IKBKAP gene is located on the long arm of chromosome 9 (9q31). People of Ashkenazi Jewish ancestry are more likely to carry the mutation causing FD.

How is it diagnosed?

Diagnosis of FD is based on recognition of both sensory and autonomic dysfunction. Prior to the discovery of the FD gene, five criteria needed to be present to confirm the diagnosis: 1) a history of Ashkenazi Jewish ancestry, 2) a smooth appearance to the tongue, 3) lack of diffuse red area after a special skin test using histamine, 4) decreased or absent knee jerks, and 5) absence of overflow tears with emotional crying.  Now only DNA testing for the mutations in the IKBKAP gene provides a definitive diagnosis.

How is it treated?

Treatment of the condition is designed to alleviate the symptoms experienced by somebody affected by the condition. There is no cure for FD. The absence of overflow tears requires frequent use of topical eye lubrication. Medication can help to regulate blood pressure, improve gastrointestinal problems and also relive some of the symptoms of dysautonomia crisis, such as nausea may be required. Surgery may be needed to protect the child from respiratory problems and to correct scoliosis. Due to decreased sense of taste, temperature and pain perception, the child will need particular protection from injury.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
FD is inherited in an autosomal recessive manner. Carriers are people that carry one copy of the mutated gene and therefore are not affected by the condition. It is recommended that couples of Ashkenazi Jewish ancestry should be offered carrier screening for FD.

Prenatal diagnosis 
Prenatal diagnosis is available for any couple who are aware that both of them are carriers.

Is there support?

Familial Dysautonomia United Kingdom (FDUK)

Email: committee@fd-uk.org
www.familialdysautonomia.co.uk

The Society is a Registered Charity in England and Wales No. 285399 (previously known as the Dysautonomia Society of Great Britain). It provides information and support for individuals and families affected by Familial Dysautonomia in the UK.  

Group details last updated August 2014.

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