Williams syndrome: features, causes, diagnosis and support

Contact, a UK charity for families with disabled children, describes Williams syndrome (also called Williams-Beuren syndrome or infantile hypercalcaemia) as a rare congenital condition caused by missing genetic material from chromosome 7. The NHS England Genomics Education Programme describes it as a developmental condition characterised by mild to moderate intellectual disability, distinctive facial features and cardiac defects.

The Williams Syndrome Foundation says it affects around 1 in 18,000 people in the UK, and Mencap says it occurs randomly. It affects everyone in different ways.

Features vary, and the clues are added together to reach a diagnosis. The groups below draw on Contact, the Williams Syndrome Foundation, Mencap and the Genomics Education Programme.

Contact says children may have a heart problem, typically supravalvular aortic stenosis, peripheral pulmonary artery stenosis or both, often present at birth or developing in early childhood. The Genomics Education Programme says supravalvar aortic stenosis occurs in 75% of affected individuals. The Williams Syndrome Foundation says in many cases the narrowing is insignificant but can be detected on cardiac ultrasound and should be monitored, and other more serious heart and vascular abnormalities can occur.

Some children develop hypercalcaemia (high blood calcium), usually within the first two years of life, which Contact says tends to correct itself after the third year. It may cause failure to thrive, feeding problems, irritability, vomiting, constipation and kidney problems. Monitoring for high blood pressure is particularly important throughout life.

Contact explains that Williams syndrome is a sporadic syndrome that occurs because of a microdeletion of chromosome 7 (7q11.23) involving 26 to 28 genes. The deletion means the protein elastin is not produced, and elastin gives strength and elasticity to blood vessel walls.

Most cases are sporadic, arising as a new deletion in the child. Mencap says Williams syndrome is not passed on from parent to child, and the Williams Syndrome Foundation describes it as non-hereditary. Contact adds that children of affected individuals would be expected to have a 50 per cent chance of inheriting it. If you are planning a family or are concerned, a clinical genetics service can explain how this applies to you.

The Williams Syndrome Foundation says clinical diagnosis is not always easy because the effects vary, but the clues can be added up to give a near-certain diagnosis. Contact says clinical diagnosis is based on typical facial features, heart problems, poor feeding and developmental delay, and confirmed by a blood sample tested for the microdeletion, using fluorescent in situ hybridisation (FISH) or microarray testing.

In the NHS the Genomics Education Programme describes testing through the National Genomic Test Directory, usually a microarray, for people whose features are strongly suggestive of a chromosomal cause. Mencap advises contacting your GP if you have concerns about your child, as early diagnosis can help you get the support you need.

There is no cure and no way to prevent the genetic change. The Williams Syndrome Foundation says early diagnosis will not prevent potential problems but can lead to a better understanding and better assistance for the child. Contact says hypercalcaemia can be addressed by a low-calcium diet, and that people need to be managed by a multidisciplinary team of specialists who help support their medical, educational and social care needs.

In practice this means regular heart and blood pressure checks, and support from services such as physical therapy, occupational therapy and speech and language therapy, as Mencap notes physical therapy and speech and language therapy can help people develop as they grow up. The Williams Syndrome Foundation says some children are educated in mainstream schools with assistance, but the majority require the support offered in specialist schools.

Mencap says that with the right support, people with Williams syndrome can live a fulfilled life, in the way they choose. Contact says that, despite relatively good verbal and social skills, most adults are unable to live independently and require ongoing support and supervision in everyday activities. The Williams Syndrome Foundation says people can develop physical and mental health problems later in life, including anxiety and depression.

The Williams Syndrome Foundation is a UK registered charity that provides information and support for individuals with Williams syndrome, their families and professionals.

Speak to a GP or health visitor if your baby or child has several of the early signs: poor feeding, excessive vomiting, slow weight gain, constipation, hernias, sleep problems or delayed development, and ask about further assessment. For anyone known to have Williams syndrome, new breathlessness, chest pain, fainting or any sudden change in health needs prompt medical assessment through NHS 111 or, in an emergency, 999.

On the NHS, care is usually coordinated by a paediatrician or clinical genetics service with cardiology, developmental, educational and community therapy input, and in adulthood through GP and learning disability services. Genomic testing is arranged through NHS genomic laboratory hubs. Private genetics and cardiology reviews are available to some families for second opinions, but the multidisciplinary NHS and education team remains central to long-term support.