Williams Syndrome

Williams syndrome is a genetic condition that affects the body’s typical growth and development. It can affect many parts of the body, including the heart and blood vessels. Children who have Williams syndrome often have mild-to-moderate intellectual disability, distinctive facial features, and certain behavioral characteristics such as an outgoing personality.

Children with Williams syndrome can also have a variety of different heart conditions, but two common conditions narrow the blood vessels (pulmonary arteries) that carry blood away from the heart to the rest of the body. They are:

• Supravalvular aortic stenosis, a narrowing of the aorta (the large blood vessel that carries blood from the heart to the body) that can disrupt normal blood flow from the heart to other organs and tissues and cause stress on the heart
• Pulmonary artery stenosis, a narrowing of the blood vessels that carry blood from the right ventricle (the right heart pumping chamber) to the lungs

There are a set of features that are commonly seen in children who have Williams syndrome. However, it is important to remember that every child with Williams syndrome is unique. Not all children will have all the possible features. Some children might have more significant complications while others can have fewer. These features include:

• Structural changes in the heart, such as supravalvular aortic stenosis or pulmonary artery stenosis
• Narrowing (stenosis) of other arteries in the body
• High blood pressure (hypertension)
• Developmental delays, including delays in speech, language, and motor skills
• Feeding problems or slow growth in infancy
• Intellectual disability and learning disorders
• Very friendly personality and trusting of strangers
• Short height
• Early puberty
• High calcium in the blood
• Joint hypermobility
• Differences in muscle tone (hypotonia and hypertonia)
• Attention-deficit hyperactivity disorder (ADHD)
• Anxiety or phobias
• Sensitivity to loud sounds
• Visual concerns such as hyperopia (farsightedness)
• Increased risk for problems of the urinary tract

Some children with Williams syndrome have a distinct facial appearance such as blue eyes and a broader smile. Facial differences are not a medical concern, rather a pattern noticed in the faces of many children with Williams syndrome.

Williams syndrome is caused by a change in the amount of an individual’s genetic make-up, or DNA. DNA is found in the form of structures called chromosomes. Williams syndrome occurs when a child has a small deletion or missing piece of one of their chromosomes, called chromosome 7. A genetic test report may refer to this genetic change as a 7q11.23 microdeletion.

Most often, the missing piece of chromosome 7, which causes Williams syndrome, is something that happens by chance. It is not typically inherited from either parent.

A diagnosis of Williams syndrome relies on evaluating an individual’s medical concerns and physical features. In some cases, Williams syndrome may be diagnosed in infants who have heart problems, failure to thrive, slow growth, or feeding problems.

In older children, Williams syndrome may be diagnosed after noticeable developmental delays involving speech, language, and motor difficulties prompt their doctor to recommend further evaluations. Some children with Williams syndrome also have a distinct facial appearance, and these characteristics, when combined with specific manners or behaviors, are what usually prompt genetic testing for Williams syndrome.

There is no specific cure for Williams syndrome, so care is focused on treating specific symptoms or cardiovascular problems. In addition to treating medical concerns, treatment may also involve working with speech and language, occupational, and physical therapists to address developmental needs. Children may also benefit from an individualized educational plan (IEP) through their school to support their learning progress.

Children with Williams syndrome who have a heart defect may need heart catheterization or surgery to repair the problem, including:

• Ballooning or stenting of blood vessels
• Patching of the aorta, coronary arteries, or pulmonary arteries
• A hybrid approach that involves a collaboration between the interventional cardiologist and surgeon to place stents in difficult-to-reach blood vessels

Some heart problems can develop or worsen over time, so regular visits with an experienced cardiovascular genetics team are recommended.

The life expectancy for children with Williams syndrome is increasingly positive. As we better understand the many elements impacting health and quality of life for those with Williams syndrome, all are better equipped to support and successfully manage challenges as they arise. Significant progress has been made since the condition was initially recognized and, in recent decades, is accurately diagnosed.

If your child is suspected to have Williams syndrome, Boston Children’s Center for Cardiovascular Genetics can help determine the most appropriate genetic test and guide your family through the testing process. Once your child has a diagnosis of Williams syndrome — diagnosed through Boston Children's Hospital or another institution — our multidisciplinary Williams Syndrome Clinic can create a treatment and management plan that will best meet their needs.