Noonan syndrome: what it is, symptoms, diagnosis and treatment

The NHS describes it as a rare genetic condition that causes a wide range of problems, with no cure at present but treatments that can help. It is lifelong. Some people are mildly affected while others have significant health problems.

MedlinePlus describes it as characterised by mildly unusual facial features, short stature, heart defects, bleeding problems and skeletal differences. It is caused by changes in genes, and the NHS says that sometimes the altered gene is inherited from a parent, but most children with it do not have affected parents.

The NHS lists the problems people with Noonan syndrome can have. It says they often have similar facial features, such as widely spaced eyes, drooping eyelids, low-set ears and a wide neck. Some people also have immune conditions such as lupus, vitiligo, antiphospholipid syndrome and coeliac disease.

The NHS says most people with Noonan syndrome are born with heart disease. MedlinePlus says the most common heart defect is a narrowing of the valve that controls blood flow from the heart to the lungs (pulmonary valve stenosis), and that some people have hypertrophic cardiomyopathy, where the heart muscle thickens.

The NHS says treatments for heart problems include medicines or surgery, and that people may be looked after by a heart specialist (cardiologist). It notes that severe heart problems can affect how long someone lives and that the care team can talk this through.

The NHS says it is usually diagnosed at birth or in early childhood, and sometimes people have it as an adult without realising because they have no typical features. A blood test can check for one of the altered genes that cause it, and a parent of an affected child may be offered a genetic test to see if they have it too.

Other tests that help confirm it are an electrocardiogram (ECG) and an echocardiogram to look at the heart, blood tests for clotting, and eye and hearing tests. In pregnancy, the NHS says tests such as amniocentesis or chorionic villus sampling may be offered if a parent has it, and that routine scans can sometimes help, for example if there is a lot of fluid around the baby (polyhydramnios). If a baby is found to have it, genetic counselling is offered.

The NHS says there is no cure, but there are treatments that can help manage the problems it causes, depending on which problems you have and how severe they are. You or your child may need support from a range of professionals, including a cardiologist, a haematologist and an endocrinologist, and children are under the care of a paediatrician.

• Medicines or surgery for heart problems.

• Medicine to help the blood clot.

• Growth hormone therapy for children with short height.

• Hearing aids for hearing loss.

• Glasses for vision problems.

• Speech and language therapy for any delay in talking.

• Extra support at school and as an adult if there is a learning disability.

The NHS says Noonan syndrome is caused by an altered gene. If you have Noonan syndrome there is a 1 in 2 (50%) chance of passing the altered gene to any children you have. But most children born with it do not have parents with the condition.

The NHS says to see a GP if you think you or your child might have Noonan syndrome, or if you are pregnant or planning a pregnancy and you, your partner or someone in either of your families has it.

The NHS says you or your child should have regular check-ups so any problems can be closely monitored and treated, and many people live for a long time and have a good quality of life. The Noonan Syndrome Association says it supports families and individuals affected by Noonan syndrome with information, webinars and family events.

MedlinePlus says most children diagnosed have normal intelligence, though a few have special educational needs and some have intellectual disability. It also says feeding problems in infants typically get better by age 1 or 2 years.

On the NHS, Noonan syndrome is usually diagnosed by paediatricians or clinical genetics services, with long-term care shared between cardiology, endocrinology, haematology, ophthalmology and audiology teams. Genetic counselling is available for families.

Private paediatric, cardiology and genetics consultations exist but most long-term multidisciplinary care in the UK is delivered through the NHS.