What is Williams syndrome?
Williams syndrome is a multisystem disorder involving connective tissue and the central nervous system. Williams syndrome occurs when a group of genes are missing (deleted) from one of the chromosomes (chromosome 7). The lack of these genes results in the manifestations of Williams syndrome. The connective tissue that is affected in Williams syndrome is called elastin, a structural protein in the cardiovascular system and soft tissues (skin and joints). Organs and body systems that can be impacted include, but are not limited to, the following:
- Heart and blood vessels
- Skeletal system
- Urinary system
- Stomach and intestines
- Hormonal systems
Williams syndrome occurs in about 1 in every 7,500 live-births. It occurs in equal numbers in males and females, and also appears equally in all races and ethnic groups.
What causes Williams syndrome?
Williams syndrome is caused by the absence (deletion) of about 28 genes on chromosome 7. A number of the features of Williams syndrome occur due to the deletion of the ELN gene, which is responsible for the production of the structural protein elastin. A number of other genes are deleted, such as LIMK1 (responsible for issues with visuospatial relationships), GTF2I (responsible for decreased intelligence), among others.
The vast majority of the time, Williams syndrome is caused by new mutations in the family (not inherited from a parent). Williams syndrome is an autosomal dominant disorder. This means that each child of an affected parent will have a 50% chance of also being born with the disorder. Similarly, when a child is born with Williams syndrome to unaffected parents, the child will have a 50 percent risk of passing the gene on to the next generation.
Why is Williams syndrome a concern?
Children with Williams syndrome are at risk for serious problems involving the cardiovascular system, including the following:
- Supravalvar aortic stenosis (SVAS). Narrowing of the aorta immediately after it exits the heart. This can cause problems with the heart’s ability to pump blood to the body and can lead to heart failure.
- Peripheral pulmonary artery stenosis. Narrowing of the arteries to the lungs. This makes it difficult for the heart to send blood to the lungs to get oxygen, which makes the right pumping chamber of the heart have to work significantly harder.
- Coarctation of the aorta. Narrowing of the aorta as it passes down to carry blood to the abdomen and lower limbs. This can cause problems with getting blood to the intestines, kidneys and legs. It also increases the work that the heart must do to push the blood through the narrowed area.
- Arrhythmia (or dysrhythmia). A fast, slow, or irregular heartbeat.
- Systemic artery stenosis. Narrowing of the arteries of the body. This may affect arteries in the neck and head, arms and legs, as well as arteries to the kidneys and intestines.
- Ventricular septal defect. A hole between the two main pumping chambers of the heart. This often does not require surgery, but in some cases it may.
What are the symptoms of Williams syndrome?
A deficiency of elastin in connective tissue creates most of the abnormalities in organs and body structures that may be seen with Williams syndrome. An extensive list of abnormalities can occur with the disorder; only the most common symptoms are listed below. Each child may experience symptoms differently. Symptoms may include:
Central nervous system
- Very friendly, talkative personality
- Developmental delay and decreased intelligence
- Attention deficit hyperactivity disorder
- Sensitivity to certain noises
- Fullness around the eyes
- Lacy or stellate pattern to irises
- Upturned nose
- Long philtrum
- Full prominent lips and wide mouth
- Small chin
Heart and blood vessels
- Supravalvar aortic stenosis
- Peripheral pulmonary artery stenosis
- Coarctation of the aorta
- Prolongation of the QTc interval on electrocardiogram
- Ventricular septal defect
- Abnormal mitral valve
- Narrowing of arteries to kidneys
Stomach and intestines
- Poor feeding
- Joint hypermobility
- High calcium levels
- Diabetes mellitus
The symptoms of Williams syndrome may resemble other problems or medical conditions. Always consult your child's health care provider for a diagnosis.
How is Williams syndrome diagnosed?
In addition to a complete medical history and physical examination, other diagnostic tests for Williams syndrome may include the following:
- Electrocardiogram (ECG or EKG). A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle damage.
- Echocardiography (echo). A procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and heart valves.
- Complete eye examination. An examination of the interior of the eye, performed by an ophthalmologist, using a device called a slit lamp.
- X-ray. A diagnostic test which uses invisible X-ray beams to produce images of internal tissues, bones, and organs onto film.
- DNA studies. A blood sample sent to the genetics lab can analyze chromosome 7 to see if the deletion is present that causes Williams syndrome. While not all persons with Williams syndrome have the deletion, it is rare for someone with Williams syndrome to not have the deletion.
In order to be diagnosed with Williams syndrome, your child must exhibit several characteristics. Your child's health care provider will make the diagnosis based on medical history and other factors, as well as symptoms your child may exhibit and the results of genetic testing.
Treatment for Williams syndrome
Specific treatment for Williams syndrome will be determined by your child's health care provider based on:
- Your child's age, overall health, and medical history
- Extent of the disorder
- Your child's tolerance for specific medications, procedures, or therapies
- Expectations for the course of the disease
- Your opinion or preference
At the present time, there is no cure for the disorder. Treatment is based on determining which organ systems are affected and managing the problems that arise. Recommendations for managing Williams syndrome may include the following:
- An annual echocardiogram, or echo (to monitor the heart and aorta)
- Annual evaluation by a cardiologist
- Ongoing care by a developmental pediatrician
- Monitoring for abnormalities of the kidneys and high blood pressure
- Monitoring of the skeletal system for abnormalities
- Evaluation by a gastroenterologist
- Treatment with medications for anxiety or ADHD
Genetic counseling is important for people who have Williams syndrome and have hopes to have a family. If one parent has the disorder, there is a 50 percent chance, with each pregnancy, for a child to also have Williams syndrome. Women with Williams syndrome should consult with their health care providers before pregnancy to determine if pregnancy is safe for them.
Long-term outlook for a child with Williams syndrome
Heart and blood vessel problems pose the largest threat to a person with Williams syndrome, which emphasizes the importance of regular evaluation by your child's health care provider. Consult your child's health care provider for more information regarding the specific outlook for your child.
The life expectancy of patients with Williams syndrome has not been thoroughly studied to allow for predictions of survival. However, with advances in the diagnosis, evaluation, and management of the organ abnormalities associated with Williams syndrome, the life expectancy is improving; certainly, there are patients with Williams syndrome who live into later adulthood.
Online Medical Reviewer:
Last Review Date: 01/01/0001