Williams Syndrome

What causes Williams syndrome

Williams syndrome results from a deletion of a small region of chromosome 7, usually occurring by chance when the egg or sperm forms. Most people have no family history. A person with Williams syndrome has a 50% chance of passing it to each child.

The missing ELN gene, which makes elastin, explains the blood vessel narrowing, hernias, voice quality and some facial features. Other missing genes affect brain development, calcium regulation and personality.

Features

Heart and blood vessels

• supravalvular aortic stenosis (SVAS): narrowing of the aorta just above the aortic valve, present in most people. See aortic stenosis
• pulmonary artery stenosis, which often improves with age
• narrowing of other arteries, including kidney and coronary arteries
• high blood pressure, in about half of people, sometimes from childhood
• higher risk of complications during anesthesia

Facial and physical features

• broad forehead, full cheeks, wide mouth with full lips, small chin, short upturned nose, puffiness around the eyes, star-like pattern in the iris
• small, widely spaced teeth
• short stature
• hoarse voice
• hernias, joint stiffness or looseness

Development and learning

• mild to moderate intellectual disability in most
• relative strengths in language, vocabulary, rote memory and music
• marked difficulty with visuospatial tasks such as drawing, puzzles and judging distances
• delayed speech in early childhood, then often very talkative

Personality and behavior

• very friendly and socially outgoing, sometimes overly trusting of strangers
• strong empathy
• anxiety, phobias and worries, common and often persistent
• ADHD
• hyperacusis: sensitivity to loud or sudden sounds

Other medical features

• hypercalcemia in infancy, causing irritability, vomiting, constipation and poor feeding
• feeding difficulties, reflux and colic in infancy
• constipation, diverticula and abdominal pain
• hypothyroidism and early-onset diabetes or prediabetes in adults
• strabismus (crossed eyes) and farsightedness
• kidney and bladder differences, urinary frequency
• early puberty in some children

Diagnosis

Williams syndrome is suspected from the combination of features, often after a heart murmur or SVAS is found. It is confirmed by:

• chromosomal microarray: the preferred test, showing the deletion
• FISH testing for the 7q11.23 region

After diagnosis, baseline tests include an echocardiogram, blood pressure in all four limbs, calcium and thyroid levels, kidney ultrasound, urine tests, and eye and hearing exams.

Management

There is no cure. Care is coordinated by a primary care doctor with specialists:

• cardiology: regular echocardiograms and blood pressure checks. Some need heart surgery or catheter procedures for SVAS or other narrowings
• calcium: monitoring and, if high, dietary adjustments. Avoid extra calcium and vitamin D supplements unless advised
• anesthesia precautions: heart evaluation and an experienced team before sedation or surgery
• early intervention: speech, occupational, physical and feeding therapy
• education: an individualized education program (IEP) using strengths in verbal learning and music
• mental health: treatment for anxiety and ADHD, including therapy and medicines
• safety teaching about strangers because of high social trust
• adult care: monitoring for diabetes, thyroid disease, hearing loss and high blood pressure, and support for employment and supported living

Outlook

Most people with Williams syndrome live well into adulthood, though life expectancy may be somewhat reduced, mainly due to heart and blood vessel complications. Many adults work in supported jobs, enjoy music and social activities, and live semi-independently with support.

Frequently asked questions

What is Williams syndrome?

Williams syndrome is a genetic condition caused by a missing piece of chromosome 7. It causes heart and blood vessel narrowing, distinctive facial features, learning difficulties with strengths in language and music, a very friendly personality, anxiety and sometimes high calcium in infancy.

What are the characteristics of Williams syndrome?

Common characteristics include supravalvular aortic stenosis, high blood pressure, a broad forehead, full cheeks and lips, short stature, mild to moderate intellectual disability, strong verbal and social skills, difficulty with spatial tasks, anxiety, ADHD and sensitivity to loud sounds.

Is Williams syndrome inherited?

Usually not. Most cases happen by chance, with no family history. However, a person who has Williams syndrome has a 50% chance of passing it on to each of their children. Genetic counseling is helpful for families.

What heart problems are common in Williams syndrome?

The most common is supravalvular aortic stenosis, a narrowing of the aorta just above the heart valve. Narrowing of the pulmonary arteries and other arteries, and high blood pressure, are also common. Regular cardiology follow-up is essential.

What is the life expectancy for Williams syndrome?

Most people with Williams syndrome live into adulthood and older age. Life expectancy may be somewhat shorter than average, mainly because of heart and blood vessel problems, so lifelong monitoring of the heart and blood pressure is important.