Also known as: Infantile Hypercalcaemia; Williams-Beuren syndrome
Williams syndrome is a rare congenital (present at birth) condition that is caused by missing genetic material from chromosome 7. Individuals with Williams syndrome are affected to differing degrees and display typical facial features as well as developmental delay.
Medical text written July 2011 by Dr K Metcalf, Consultant Clinical Geneticist, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK.
Individuals with Williams syndrome display typical facial features, including:
- prominent cheeks
- upturned nose
- wide mouth
- irregular, widely spaced teeth.
Children may have a heart problem, typically supravalvular aortic stenosis, peripheral pulmonary artery stenosis or both. These are often present at birth or develop in early childhood.
Some children develop hypercalcaemia (abnormally high levels of calcium), usually within the first two years of life but this tends to correct itself after the third year. Hypercalcaemia may cause failure to thrive, feeding problems, irritability, vomiting, constipation and kidney problems. A number of other health problems are more common in Williams syndrome. Monitoring for high blood pressure is particularly important throughout life.
Children with Williams syndrome are usually developmentally delayed, with most having moderate learning difficulties (see entry Learning Disability). They may be slow to develop language, but by school age their spoken language is usually a relative strength. They are often clumsy and have difficulties in the integration of visual-spatial information. Most children with Williams syndrome are outgoing and socially disinhibited towards adults, including strangers, but they tend to have poor relationships with other children.
Typical behaviour difficulties include overactivity, poor concentration and distractibility, excessive anxiety, attention seeking behaviours and high rates of preoccupations and obsessions. Many children are hypersensitive to particular sounds, a condition known as hyperacusis, including electrical noises (eg vacuum cleaners).
Despite their relatively good verbal and social skills, most adults with Williams syndrome are unable to live independently and require ongoing support and supervision in everyday activities.
Williams syndrome is a sporadic syndrome that occurs because of a microdeletion of chromosome 7 (7q11.23) involving 26 to 28 genes. This deletion results in the protein elastin not being produced. Elastin is responsible for providing strength and elasticity to blood vessel walls.
Clinical diagnosis is based on a variety of characteristics common to Williams syndrome, including the typical facial features, heart problems, poor feeding and developmental delay.
Williams syndrome is confirmed by a taking a blood sample, which is then tested to see if the relevant microdeletion is present. Fluorescent in situ hybridisation (FISH) or microarray comparative hybridisation (array-CGH) are two tests that can be used to see if there is material missing from chromosomes.
There is no cure for Williams syndrome. Hypercalcaemia can be addressed by a low-calcium diet. Individuals will need to be managed by a multidisciplinary team of specialists who can help support their medical, educational and social care needs.
Most cases are sporadic and due to a new chromosome deletion arising in the child. Children of affected individuals however would be expected to have a 50 per cent chance of inheriting Williams syndrome.
For couples who already have a child with Williams syndrome seeking reassurance, or for pregnancy in someone affected by Williams syndrome, prenatal diagnosis by FISH testing of chorionic villus biopsy or amniocentesis is possible.
Williams Syndrome Foundation
The Foundation is a Registered Charity in England and Wales No. 281014. It provides information and support for individuals with Williams Syndrome, their families and professionals. The Foundation actively supports research into the educational, behavioural, social, scientific and medical aspects of the Syndrome.
Group details last updated September 2014.
As Williams syndrome is a metabolic disease, support and advice are also available from Climb (see entry Inherited Metabolic diseases).