Williams Syndrome - genetic condition with inadequate mental development
The condition was first discovered by Dr. J C P Williams and is also known by the names of Williams-Beuren syndrome, Elfin Facies Syndrome and Supravalvar aortic stenosis syndrome. The prevalence rate of Williams syndrome is equal in both girls and boys. It is found in the ratio of 1:8,000 births.
Williams syndrome is marked by mental retardation associated with a very high degree of social empathy. The individuals suffering from WS are unperturbed by the physical appearance of other people and are overtly friendly. They take undue interest in the activities of other people and easily connect with others. They suffer from learning disabilities. They have difficulty in reconstructing visual patterns leading to problem in solving puzzles and drawing. Their vocabulary in describing abstract things is severely limited. However, their short term memory and practical vocabulary is very strong. They are good at learning things by repetition and do exceedingly well in the field of music. Infants with WS have increased blood calcium levels and suffer from abdominal colics. The main problem associated with WS is the thinning of arteries leading to various circulatory disorders. The patients of WS have typical facial features associated with certain behavioral problems.
Physical and behavioral symptoms of Williams syndrome
Facial Features in Williams Syndrome
- A small nose with flattened nasal bridge
- Swelling around the eyes with a fold of skin covering the nasal end of the eyes (epicanthal fold)
- A star like pattern in the iris of the eye
- Widely spaced, crooked or missing teeth
- Full lips with a wide mouth and full cheeks
- A prominent groove in the skin from the nose to the upper end of the lips (philthrum)
- Small chin
Other physical features include:
- A short stature
- slanting shoulders with a long neck
- depressed chest (pectus excavitum)
- reduced movement of the joints
- unusual curvature of the spine
- inward bending of the little finger (clinodactyly)
Behavioral problems include:
- Tendency to get distracted easily. Almost 50% patients of WS suffer from attention deficit disorders.
- High level of anxiety
- Analytical disability
- Unusually friendly
- Phobic to loud sound
- difficulty in reconstructing visual patterns
Signs of WS:
- Narrowing of blood vessels leading to conditions like supravalvular aortic stenosis and pulmonary stenosis. If not corrected timely, these conditions may lead to heart failure.
- High blood pressure
- Elevated levels of calcium in blood may lead to stiff muscles, kidney stones and seizures.
- Hypermetropia or farsightedness
- Star like pattern in the eye
- Low birth weight and slow gain in weight
Cause of Williams Syndrome
Deletion of a particular part of ‘chromosome 7’ leads to the development of Williams Syndrome. The deleted portion consists of as many as 25 genes whose loss results in the typical features of the disease. The important genes that are absent in patients of Williams Syndrome include ELN, CLIP2, GTF21, GTF21RD1 and LIMK1. The circulatory disorders, specially the supravalvular aortic stenosis, associated with Williams Syndrome are particularly attributed to the loss of ELN gene. This gene produces ‘elastin’, a connective tissue protein which provides elasticity to the blood vessels. Its absence makes the vessel walls rigid leading to stenosis. The absence of the ELN gene also results in abnormalities of connective tissue leading to stiff muscles, farsightedness, various joint problems and a slack and lax skin. The loss of CLIP2, GTF21, GTF21RD1 and LIMK1 genes is the reason behind the behavioral problems associated with the disease. The deletion of GTF21RD21 gene is responsible for the typical facial features of Williams Syndrome. Another gene, known as NCF1 plays an important part in the development of hypertension in the patients of WS. If this particular gene is included in the deleted portion of chromosome 7, then chances of developing high blood pressure are low. So the loss of NCF1 is actually a boon for patients of Williams Syndrome.
Williams Syndrome is an ‘autosomal dominant condition’. Alteration in a single copy of chromosome 7 can cause the disease. Therefore there are 50% chances of individuals suffering from Williams syndrome passing the disease to their off springs. However, a random genetic mutation taking place at the time of formation of an egg or a sperm, rather than inheritance, is more likely the reason behind the development of this condition.
Tests for identifying Williams Syndrome
The confirmatory test for diagnosing Williams Syndrome is ‘fluorescent in situ hybridization’ popularly known as FISH. It tests the DNA to identify the absence of ELN gene from chromosome number 7.
Besides FISH, other tests used to recognize the associated signs of Williams Syndrome are:
- Checking the blood pressure
- Echocardiography along with colored Doppler for detecting stenosis in any blood vessel
- Ultrasonography of kidneys to detect any stone
- Blood calcium levels to rule out any elevation
Treatment for Williams Syndrome
Williams Syndrome is an incurable disease. Treatment is targeted towards the alleviation of the symptoms associated with the disease. Regular monitoring of the blood pressure and diagnostic tests at a specified interval of time are essential to rule out cardiovascular complications like stenosis of blood vessels and heart failure. Blood calcium levels are to be maintained at a normal level and necessary treatment should be administered in case their levels are raised. Regular physiotherapy is advised to maintain the normal movement of the joints. Specially designed developmental programs, keeping in mind the profile of the patient, may greatly benefit the children suffering from Williams syndrome.
Racial biases research in patients of Williams Syndrome
Research programs have thrown light on an important aspect in the profile of the patients of Williams syndrome. These children exhibited no racial bias though they did show discrimination based on gender. Studies have shown that racial bias is associated with social fear. The part of the brain, called as amygdala is responsible for the reactions of the body to social fear. In patients of Williams syndrome, the activity of amygdala is found to be abnormal. Therefore these patients do not react negatively to social fear and do not show any form of bias towards people of other races.