Williams syndrome is a rare genetic disorder. Like Down's syndrome it is caused by an abnormality in chromosomes, and shows a wide variation in ability from person to person. Individuals diagnosed with Williams syndrome have a unique pattern of emotional, physical and mental strength’s and weaknesses. For parents, teachers, and support people, learning about this pattern can be a key to understanding an individual with Williams and in helping them achieve their full potential.

It is a non-hereditary syndrome which occurs at random and can affect brain development in varying degrees, combined with some physical effects or physical problems. These range from lack of co-ordination, slight muscle weakness, and possible heart defects and occasional kidney damage. Hypercalcemia, a high calcium level, is often discovered in infancy, and normal development is generally delayed.

The incidence is approximately 1 in 20,000. As the medical professional and the public is alerted more and more cases are being diagnosed yearly.


Diagnosis is not easy as effects vary considerably, but the different clues can be added up to produce a near-certainty. The cause of Williams syndrome is a micro deletion of part of chromosome 7 which includes the Elastin Gene. A blood test (called the FISH technique) can establish if the Elastin Gene is in fact missing.

Physical Clues

Facial features:

All the children have a facial similarity, referred to as "elfin" features. They include a wide mouth with large, slack bottom lip; very retrousse nose with flattened bridge; slightly "bulgy" cheeks; irregular teeth widely spaced; sometimes a squint.

Early problems:

These can include low birth weight, often after being "late for dates", slow weight gain. Sometimes weight loss; below average growth; very slow feeding, restless sleeping, and irritability; sometimes a hernia, a squint and excessive vomiting leading to dehydration and constipation. A raised calcium level is found in some babies.

Heart problems:

All Williams syndrome individuals appear to have a slight narrowing of the aorta above the valve, in many cases insignificant, but occasionally leading to more serious heart defects.

Psychological Clues

Hyperactivity in early years:

  • extreme uninhibited behaviour
  • excessive talking, in an inappropriate and "adult" manner
  • over-friendliness with strangers
  • compulsion to talk to adults, while being unable to make friends with peers
  • high verbal ability leading to artificial expectations of matching mental ability
  • obsessional interest in certain things: e.g. cars, ambulances, vacuums, wheels etc.
  • fear of heights, open stairs, uneven surfaces
  • very short concentration span adding to learning difficulties, high distractibility
  • emotional immaturity exhibited by over-reaction to events and exaggerated displays of fear, excitement, sadness, happiness etc.

Hypersensitivity to noise:

This is the clue most common to all Williams syndrome children. About 90% show great distress on hearing sudden loud noises, such as guns firing, balloons bursting, Christmas crackers, fireworks etc.


Early diagnosis means better understanding of the problems which may arise, leading to a happier life for the child and relief and support for the parents. There is no "cure" for Williams syndrome as it is caused by a genetic/chromosomal defect. When hypocalcaemia (high blood calcium levels) occurs in the first year or two of life, a low calcium diet is prescribed.

Individuals with Williams syndrome can develop health problems related to the syndrome and also ordinary health problems unrelated to the syndrome. It is important to make good use of local resources (e.g. general practitioners, health visitors, local education departments etc.) in addition to using specialists and experts in Williams syndrome. Continuing further education can help to realize full potential.


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Canadian Association for Williams Syndrome