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Williams Syndrome

Fact Sheet

What is Williams Syndrome?

Williams Syndrome is a rare, congenital (present at birth) disorder characterized by medical, physical and developmental problems including an impulsive and outgoing (excessively social) personality, limited spatial skills and motor control, and intellectual disability (e.g., developmental delay, learning disabilities, and attention deficit disorders). Symptoms vary among individuals.

Most people with Williams Syndrome will have a mild to severe learning disability. Young children with Williams Syndrome often experience developmental delays. Milestones such as walking, talking and toilet training are often achieved somewhat later than is considered normal. Distractibility, a common problem in mid-childhood, appears to get better as the children get older.

Older children and adults with Williams Syndrome often demonstrate intellectual “strengths” and “weaknesses.” There are some intellectual areas such as speech, long term memory, and social skills in which performance is quite strong, while other intellectual areas, such as fine motor and spatial relations are significantly delayed. Scientists have learned that most individuals with Williams Syndrome have a deletion of genetic material on Chromosome 7 which includes the elastin gene.

How is it manifested?

Physical Indicators:

  • facial features “elfin” like
  • early problems: low weight, weight loss, below average growth
  • heart and blood vessel problems
  • hypercalcemia (elevated blood calcium levels)
  • low birth-weight/low weight gain
  • dental abnormalities
  • musculoskeletal problems
  • kidney abnormalities
  • hernias
  • hyperacusis

Behaviour Indicators:

  • irritability
  • feeding problems
  • overly friendly (excessively social) personality
  • developmental delay, learning disabilities, and attention deficit
  • high verbal ability
  • sensitivity to loud noises

Who is affected?

It is estimated to occur in 1 in 8000 births. It is known to occur equally in both males and females in every culture.

How is it diagnosed or detected?

Many individuals with Williams Syndrome remain undiagnosed or are diagnosed at a relatively late age. This is of concern since individuals with Williams Syndrome can have significant and possibly progressive medical problems. When the characteristics of Williams Syndrome are recognized, referral to a clinical geneticist for further diagnostic evaluation is appropriate. The clinical diagnosis can be confirmed by a blood test. The technique known as Fluorescent In Situ Hybridisation (FISH), a diagnostic test of the DNA, detects the elastin deletion on Chromosome 7 in 95% to 98% of individuals with Williams Syndrome.

Additional Resources:

Williams Syndrome Association (WSA)
The WSA is the only group in the United States devoted exclusively to improving the lives of individuals with Williams Syndrome and their families. The WSA supports research into all facets of the syndrome, and the development of the most up-to-date educational materials regarding Williams Syndrome.

Canadian Association for Williams Syndrome (CAWS) –
The Canadian Association of Williams Syndrome (CAWS) was founded by a group of parents in 1984. CAWS is a national federation of the provinces in Canada that provides support to Williams Syndrome individuals and their families.

Books and Literature:

Williams Syndrome: Approaches to Intervention
By Eleanor Semel and Sue R. Rosner

Journey from Cognition to Brain to Gene: Perspectives from Williams Syndrome
By Ursula Bellugi and Marie I. St. George

Fulfilling Dreams – The WS Parent Handbook
By Barbara Scheiber


Williams Syndrome Information for Teachers
By Karen Levine
Available at

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