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Reviewed April 2006
What is Andersen-Tawil syndrome?
Anderson-Tawil syndrome is a disorder that causes episodes of muscle weakness (periodic paralysis), changes in heart rhythm (arrhythmia), and developmental abnormalities. The most common changes affecting the heart are ventricular arrhythmia, which is a disruption in the rhythm of the heart's lower chambers, and long QT syndrome. Long QT syndrome is a heart condition that causes the heart (cardiac) muscle to take longer than usual to recharge between beats. If untreated, the irregular heartbeats can lead to discomfort, fainting (syncope), or cardiac arrest.
Physical abnormalities associated with Andersen-Tawil syndrome typically affect the head, face, and limbs. These features often include a very small lower jaw (micrognathia), dental abnormalities, low-set ears, widely spaced eyes, and unusual curving of the fingers or toes (clinodactyly). Some affected people also have short stature and an abnormal curvature of the spine (scoliosis).
Two types of Andersen-Tawil syndrome are distinguished by their genetic causes. Type 1, which accounts for about 60 percent of all cases of the disorder, is caused by mutations in the KCNJ2 gene. The remaining 40 percent of cases are designated as type 2; the cause of these cases is unknown.
How common is Andersen-Tawil syndrome?
Andersen-Tawil syndrome is a rare genetic disorder; its incidence is unknown. About 100 people with this condition have been reported worldwide.
What genes are related to Andersen-Tawil syndrome?
Mutations in the KCNJ2 gene cause Andersen-Tawil syndrome.
The KCNJ2 gene provides instructions for making a protein that forms a channel across cell membranes. This channel transports positively charged atoms (ions) of potassium into muscle cells. The movement of potassium ions through these channels is critical for maintaining the normal functions of muscles used for movement (skeletal muscles) and cardiac muscle. Mutations in the KCNJ2 gene alter the usual structure and function of potassium channels or prevent the channels from being inserted correctly into the cell membrane. Many mutations prevent a molecule called PIP2 from binding to the channels and effectively regulating their activity. These changes disrupt the flow of potassium ions in skeletal and cardiac muscle, leading to the periodic paralysis and irregular heart rhythm characteristic of Andersen-Tawil syndrome.
Researchers have not determined the role of the KCNJ2 gene in bone development, and it is not known how mutations in the gene lead to the developmental abnormalities often found in Andersen-Tawil syndrome.
Read more about the KCNJ2 gene.
How do people inherit Andersen-Tawil syndrome?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In some cases, a person with Andersen-Tawil syndrome inherits the mutation from one affected parent. Other cases result from new mutations in the KCNJ2 gene. These cases occur in people with no history of the disorder in their family.
Where can I find information about diagnosis or management of Andersen-Tawil syndrome?
These resources address the diagnosis or management of Andersen-Tawil syndrome and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about Andersen-Tawil syndrome?
You may find the following resources about Andersen-Tawil syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for Andersen-Tawil syndrome?
What if I still have specific questions about Andersen-Tawil syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding Andersen-Tawil syndrome?
arrhythmia ; autosomal ; autosomal dominant ; cardiac ; cardiac arrest ; cell ; cell membrane ; channel ; clinodactyly ; fainting ; gene ; incidence ; inherited ; ions ; long QT syndrome ; lower jaw ; micrognathia ; molecule ; muscle cells ; mutation ; potassium ; protein ; scoliosis ; short stature ; stature ; syncope ; syndrome
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (9 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.