About williams-beuren syndrome
What is williams-beuren syndrome?
Williams syndrome, also known as Williams-Beuren syndrome, is a rare genetic disorder characterized by growth delays before and after birth (prenatal and postnatal growth retardation), short stature, a varying degree of mental deficiency, and distinctive facial features that typically become more pronounced with age. Such characteristic facial features may include a round face, full cheeks, thick lips, a large mouth that is usually held open, and a broad nasal bridge with nostrils that flare forward (anteverted nares). Affected individuals may also have unusually short eyelid folds (palpebral fissures), flared eyebrows, a small lower jaw (mandible), and prominent ears. Dental abnormalities may also occur including abnormally small, underdeveloped teeth (hypodontia) with small, slender roots.
Williams syndrome may also be associated with heart (cardiac) defects, abnormally increased levels of calcium in the blood during infancy (infantile hypercalcemia), musculoskeletal defects, and/or other abnormalities. Cardiac defects may include obstruction of proper blood flow from the lower right chamber (ventricle) of the heart to the lungs (pulmonary stenosis) or abnormal narrowing above the valve in the heart between the left ventricle and the main artery of the body (supravalvular aortic stenosis). Musculoskeletal abnormalities associated with Williams syndrome may include depression of the breastbone (pectus excavatum), abnormal side-to-side or front-to-back curvature of the spine (scoliosis or kyphosis), or an awkward gait. In addition, most affected individuals have mild to moderate mental retardation; poor visual-motor integration skills; a friendly, outgoing, talkative manner of speech; a short attention span; and are easily distracted.
In most individuals with Williams syndrome, the disorder appears to occur spontaneously for unknown reasons (sporadically). However, familial cases have also been reported. Sporadic and familial cases are thought to result from deletion of genetic material from adjacent genes (contiguous genes) within a specific region of chromosome 7 (7q11.23).
What are the symptoms for williams-beuren syndrome?
People with Williams syndrome typically have difficulty with visual-spatial tasks such as drawing and assembling puzzles, but they tend to do well on tasks that involve spoken language, music, and learning by repetition (rote memorization). Affected individuals have outgoing, engaging personalities and tend to take an extreme interest in other people. Attention deficit disorder (ADD), problems with anxiety, and phobias are common among people with this disorder.
Young children with Williams syndrome have Distinctive facial features including
- a broad forehead,
- a Short nose with a broad tip,
- full cheeks, and
- a wide mouth with full lips.
Many affected people have dental problems such as teeth that are small, widely spaced, crooked, or missing. In older children and adults, the face appears longer and more gaunt.
A form of cardiovascular disease called supravalvular aortic stenosis (SVAS) occurs frequently in people with Williams syndrome. Supravalvular aortic stenosis is a narrowing of the large blood vessel that carries blood from the heart to the rest of the body (the aorta). If this condition is not treated, the aortic narrowing can lead to
- shortness of breath,
- chest pain, and
- heart failure.
Other problems with the heart and blood vessels, including High blood pressure (hypertension), have also been reported in people with Williams syndrome.
Additional signs and symptoms of Williams syndrome include abnormalities of connective tissue (tissue that supports the body's joints and organs) such as joint problems and soft, loose skin.
Affected people also may have
- increased calcium levels in the blood (hypercalcemia) in infancy,
- developmental delays,
- problems with coordination, and
- Short stature.
Medical problems involving the eyes and vision, the digestive tract, and the urinary system are also possible.
What are the causes for williams-beuren syndrome?
Williams syndrome is caused by the deletion of genetic material from a specific region of chromosome 7. The deleted region includes 26 to 28 genes, and researchers believe that a loss of several of these genes probably contributes to the characteristic features of this disorder.
CLIP2, ELN, GTF2I, GTF2IRD1, and LIMK1 are among the genes that are typically deleted in people with Williams syndrome. Researchers have found that loss of the ELN gene is associated with the connective tissue abnormalities and cardiovascular disease (specifically supravalvular aortic stenosis) found in many people with this disease. Studies suggest that deletion of CLIP2, GTF2I, GTF2IRD1, LIMK1, and perhaps other genes may help explain the characteristic difficulties with visual-spatial tasks, unique behavioral characteristics, and other cognitive difficulties seen in people with Williams syndrome. Loss of the GTF2IRD1 gene may also contribute to the distinctive facial features often associated with this condition.
Researchers believe that the presence or absence of the NCF1 gene on chromosome 7 is related to the risk of developing hypertension in people with Williams syndrome. When the NCF1 gene is included in the part of the chromosome that is deleted, affected individuals are less likely to develop hypertension. Therefore, the loss of this gene appears to be a protective factor. People with Williams syndrome whose NCF1 gene is not deleted have a higher risk of developing hypertension.
The relationship between other genes in the deleted region of chromosome 7 and the signs and symptoms of Williams syndrome is under investigation or unknown.
What are the treatments for williams-beuren syndrome?
Many different caregivers can be involved in taking care of your child, including a:
- Cardiologist -- a doctor who treats heart problems
- Endocrinologist -- a doctor who treats hormone problems
- Gastroenterologist -- a doctor who treats gastrointestinal problems
- Ophthalmologist -- a doctor who treats eye problems
- Speech and language therapist
- Occupational therapist
- Physical therapist
Some of the treatments your child might need:
- A diet low in calcium and vitamin D to bring down high calcium levels in the blood
- Medicine to lower blood pressure
- Special education, including speech and language therapy
- Physical therapy
- Surgery to fix a blood vessel or heart problem
Your child might need treatments for other symptoms, too.
What are the risk factors for williams-beuren syndrome?
Most cases of Williams syndrome are not inherited, but occur as random events during the formation of reproductive cells (eggs or sperm) in a parent of an affected individual. These cases occur in people with no history of the disorder in their family.
Williams syndrome is considered an autosomal dominant condition because one copy of the altered chromosome 7 in each cell is sufficient to cause the disorder. In a small percentage of cases, people with Williams syndrome inherit the chromosomal deletion from a parent with the condition.
Is there a cure/medications for williams-beuren syndrome?
Medical conditions can affect the lifespan of those with Williams syndrome. Calcium deposits can cause kidney problems, and narrowed blood vessels can cause heart failure. The majority of affected people have some degree of intellectual disability. Learning self-help skills and getting early intervention in school can help encourage independence. Some people with Williams syndrome will need to live with a caregiver or in a supervised home.
People with Williams syndrome should avoid taking extra calcium and vitamin D. This is because blood levels of these substances are already high.