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.
What are the clues: Physical
- 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.
What are the clues: Psychological
- 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, trains, hoovers, 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.