Williams syndrome is a rare neurodevelopmental disorder that happens with the deletion of about 26 genes from the long arm of chromosome 7. The disease affects approximately 1 in 7,500 to 1 in 20,000 newborns. People affected with this disease share some common physical features. For example, their facial appearance is characteristically “elfin", and their nasal bridge is usually low. Unfortunately, people affected by Williams syndrome have delays in their development but strong language skills. These people are usually very cheerful and have no problems in communication to strangers. They are openhearted, talkative and extremely carefree. However, their health is severely disturbed since many of them have serious cardiovascular problems, namely supravalvular aortic stenosis and transient hypercalcaemia. These diseases are described as an abnormal narrowing of the aortic valve opening and elevated calcium level in the blood, respectfully.
Signs and symptoms of Williams syndrome
The most common symptoms include mental disability, heart defects, and typical facial features: spaced teeth, a long philtrum, and flattened nasal bridge. Their health problems include heart murmurs and the narrowing of major blood vessels, gastrointestinal problems, bed wetting, urinary difficulties, dental irregularities and defective tooth enamel, various hormonal problems, and diabetes.People with Williams disease are often afraid of loud noise and contribute to higher rates of left-handedness and left-eye dominance, than general population.
Causes and prevention
Williams syndrome is caused by the deletion of genetic material from the region q11.23 of chromosome 7. This region includes more than 25 genes but some of them, such as CLIP2, ELN, GTF2I, GTF2IRD1, and LIMK1, are typically deleted in people suffering from this disease. Deletion of some of these genes is responsible for distinctive physical features, while the other contribute to various health conditions, behavioral characteristics, learning disabilities, and other cognitive difficulties. The gene is sometimes passed from a carrier to a child. A person with Williams syndrome has a 50% chance of passing the disorder on to offspring. However, in many cases the parents may not have a family history of the condition, and the deletion occurs as a random mutation.
If one of the parents has a family history of Williams syndrome, the couple should take genetic counseling to determine whether some of them carry a gene for this disorder. There is no cure for the disorder and the only way to prevent random mutations is possibly to adopt a healthy lifestyle. However, there is no certain way to prevent these random changes in genetic material.