What is Williams syndrome?

Williams syndrome is a genetic disorder.

In most cases it’s caused by a small bit missing from chromosome 7. And in most cases this happens by chance while the eggs or sperm are being formed in the parents’ bodies before conception. But people with Williams syndrome have a 50% chance of passing it on to their children.

Williams syndrome is a rare condition that happens in 1 in 7500-20 000 births. It affects boys and girls equally.

This syndrome is sometimes known as Williams-Beuren syndrome. It was first described by Dr Williams and colleagues in 1961, and Dr Beuren in 1962.

Signs and symptoms of Williams syndrome

Physical characteristics
Young children with Williams syndrome have distinctive facial features. These include:

  • broad forehead
  • small upturned nose
  • wide mouth with full lips
  • small chin
  • puffiness around the eyes.

Other physical features include:

  • low muscle tone and loose joints – joint stiffness sometimes develops as children get older
  • short stature compared with other people in the family, although children sometimes catch up a bit in later childhood
  • dental problems like small, widely spaced teeth, or crooked or missing teeth.

Intellectual ability signs
About three-quarters of people with Williams syndrome have intellectual disability. Many children with Williams syndrome also have:

  • speech delay – a child’s first word might come as late as three years old. The child then usually develops relatively good verbal abilities, which can be used to help other areas of learning
  • developmental delays – for example, with walking and toilet training
  • difficulties with fine motor skills
  • difficulty with tasks like drawing or doing puzzles.

Behavioural signs
Children with Williams syndrome often have behavioural signs like:

Medical concerns linked to Williams syndrome
People with Williams syndrome can have:

  • problems with their hearts or blood vessels, which can range from minor to severe and needing surgery
  • low birth weight and failure to thrive
  • feeding problems including colic and reflux
  • an underactive thyroid gland
  • increased risk of diabetes
  • vision problems
  • elevated blood calcium levels in childhood
  • sensitive hearing.
Children with Williams syndrome have strengths in areas involving speech, music and long-term memory. They also have outgoing, social personalities.

Diagnosis and testing for Williams syndrome

Health professionals can diagnose Williams syndrome by looking for the syndrome’s key characteristics – distinctive facial features, heart problems, feeding difficulties and developmental delay.

They can confirm Williams syndrome with genetic testing.