Williams Syndrome

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Williams syndrome is a rare, genetic, developmental disorder affecting various parts of the body. The majority of people with Williams syndrome have distinctive facial features, some degree of mental retardation, and cardiovascular complications. No treatment exists that prevents the syndrome. Rather, interventions focus on managing the complications. People with Williams syndrome can live into adulthood.

Abnormal regulation of the amygdala in participants with Williams syndrome (right) compared to controls (left). The amygdala activates more for threatening scenes (bottom), but less for threatening faces (top). Source: NIH


Contents

Other Names

Williams syndrome is also called Williams-Beuren syndrome.

Symptoms

Williams syndrome results in a characteristic “elfish” appearance of the face. These features include broad forehead, a short nose with a broad tip, full cheeks, wide mouth with full lips, and widely spaced, crooked, or missing teeth. Other signs of the condition include the following:

  • mild to moderate mental retardation and/or learning disabilities (such as difficulty with visual-spatial tasks)
  • unique psychosocial characteristics (a desire for social interaction and conversation with a poor understanding of social dynamics and a lack of social inhibition)
  • heart and blood vessel problems (such as supravalvular aortic stenosis and high blood pressure)
  • high calcium levels in the blood

Causes

Williams syndrome is caused by a deletion of more than 25 genes from a specific region of chromosome 7. The syndrome manifests when the mutated chromosome is inherited from either the mother or father; the presence of one normal copy of chromosome 7 is insufficient to prevent the syndrome.

The loss of the ELN gene is associated with some of the characteristic facial features, connective tissue abnormalities and supravalvular aortic stenosis. Connective tissue joins tissues to one another and provides cushioning to joints. The synovial fluid in the knee, tendons, and ligaments are all examples of connective tissue. A stenosis in the heart is a blockage that slows blood flow. The deletion of LIMK1, GTF2I, GTF2IRD1, and CLIP2 causes the difficulty with visual-spatial tasks, unique behavioral characteristics, and other cognitive problems. Loss of the GTF2IRD1 gene may also contribute to the distinctive facial features often associated with this condition.

Diagnosis

Doctors use the symptoms of Williams syndrome to make a diagnosis. The distinctive facial characteristics of Williams syndrome are apparent at birth. The children are often hyperactive, overly friendly, and inattentive. They may also show signs of mental retardation and may have a small head size and brain (microencephaly). Some children may have a history of frequent urination and wetting the pants.

The deletion in chromosome 7 can be detected by a technique called fluorescent hybridization. This procedure is done after birth and uses a fluorescent marker that binds to and illuminates part of the chromosome. The chromosome can be examined under a microscope and easily visualized because of the marker. Another test, called karyotyping, is also performed. This test stains chromosomes with color markers that allow structural defects to be seen.

Treatment

There is no cure nor standard course of treatment for Williams syndrome. Treatment is tailored to specific symptoms.

Expected Outcome

The expected outcome varies widely depending upon the severity of the disease. Due to mental retardation, many people with the syndrome must live under supervision from a caregiver.

The most common causes of death in people with Williams syndrome are related to the cardiovascular complications. The incidence of death due to cardiovascular disease is 25–100 times greater in people with the syndrome compared to those without, but the risk in people with Wiliams syndrome is still very low.[1]

References

  1. Wessel A, Gravenhorst V, Buchhorn R. Risk of sudden death in the Williams-Beuren syndrome. Am J Med Genet A. 2004;127(3):234-7. [http:pubmed.gov/ 15150772 Abstract]

External Links

National Institute of Neurological Disorders and Stroke

Gene Reviews

New York Times Article

Williams Syndrome Association

Williams Syndrome Foundation

Medpedia-logo.gif The basis of this article is contributed from Medpedia.com These articles are licensed under the GNU Free Documentation License It may have since been edited beyond all recognition. But we thank Medpedia for allowing its use.
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