domingo, 12 de julio de 2015

Sheldon-Hall syndrome - Genetics Home Reference

Sheldon-Hall syndrome - Genetics Home Reference

Genetics Home Reference: your guide to understanding genetic conditions

Sheldon-Hall syndrome

What is Sheldon-Hall syndrome?

Sheldon-Hall syndrome, also known as distal arthrogryposis type 2B, is a disorder characterized by joint deformities (contractures) that restrict movement in the hands and feet. The term "arthrogryposis" comes from the Greek words for joint (arthro-) and crooked or hooked (gryposis). "Distal" refers to areas of the body away from the center. The characteristic features of this condition include permanently bent fingers and toes (camptodactyly), overlapping fingers, and a hand deformity called ulnar deviation in which all of the fingers are angled outward toward the fifth (pinky) finger. Inward- and upward-turning feet (a condition called clubfoot) is also commonly seen in Sheldon-Hall syndrome. The specific hand and foot abnormalities vary among affected individuals; the abnormalities are present at birth and generally do not get worse over time.
People with Sheldon-Hall syndrome also usually have distinctive facial features, which include a triangular face; outside corners of the eyes that point downward (down-slanting palpebral fissures); deep folds in the skin between the nose and lips (nasolabial folds); and a small mouth with a high, arched roof of the mouth (palate). Other features that may occur in Sheldon-Hall syndrome include extra folds of skin on the neck (webbed neck) and short stature.
Sheldon-Hall syndrome does not usually affect other parts of the body, and intelligence and life expectancy are normal in this disorder.

How common is Sheldon-Hall syndrome?

The prevalence of Sheldon-Hall syndrome is unknown; however, it is thought to be the most common type of distal arthrogryposis. About 100 affected individuals have been described in the medical literature.

What genes are related to Sheldon-Hall syndrome?

Sheldon-Hall syndrome can be caused by mutations in the MYH3TNNI2TNNT3, or TPM2 gene. These genes provide instructions for making proteins that are involved in muscle tensing (contraction).
Muscle contraction occurs when thick filaments made of proteins called myosins slide past thin filaments made of proteins called actins. The MYH3 gene provides instructions for making a myosin protein that is normally active only before birth and is important for early development of the muscles.
The process of muscle contraction is controlled (regulated) by other proteins called troponins and tropomyosins, which affect the interaction of myosin and actin. Certain troponin proteins are produced from the TNNI2 and TNNT3 genes. The TPM2 gene provides instructions for making a tropomyosin protein.
Mutations in the MYH3TNNI2TNNT3, or TPM2 gene likely interfere with normal muscle development or prevent muscle contractions from being properly controlled, resulting in the contractures and other muscle and skeletal abnormalities associated with Sheldon-Hall syndrome. It is unknown why the contractures mainly affect the hands and feet or how these gene mutations are related to other features of this disorder.
Read more about the MYH3TNNI2TNNT3, and TPM2 genes.

How do people inherit Sheldon-Hall 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 about 50 percent of cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Where can I find information about diagnosis or management of Sheldon-Hall syndrome?

These resources address the diagnosis or management of Sheldon-Hall syndrome and may include treatment providers.
You might also find information on the diagnosis or management of Sheldon-Hall syndrome inEducational resources and Patient support.
General information about the diagnosis and management of genetic conditions is available in the Handbook.
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 Sheldon-Hall syndrome?

You may find the following resources about Sheldon-Hall 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 Sheldon-Hall syndrome?

  • arthrogryposis multiplex congenita, distal, type 2B
  • DA2B
  • distal arthrogryposis type 2B
  • SHS
For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines and How are genetic conditions and genes named? in the Handbook.

What if I still have specific questions about Sheldon-Hall syndrome?

Where can I find general information about genetic conditions?

What glossary definitions help with understanding Sheldon-Hall syndrome?

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
References (5 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

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