Clinical Genetics

Noonan Syndrome

Introduction to Noonan Syndrome

Noonan syndrome is a genetic condition which causes various health problems. The condition is always present from birth but may not be noticed until the baby is older.

Written by Doctify Team 27/04/2020

What is Noonan Syndrome?

Noonan syndrome is a genetic condition which causes various health problems. The condition is always present from birth but may not be noticed until the baby is older. Diagnosis is usually made by the characteristic visual appearance that is typical in noonan syndrome and presence of certain defects; these include a short stature, unique facial features (drooping eyelids, broad forehead) and congenital heart defects. It is fairly rare with 1 in 1’000-2’500 births being affected.

What are the causes for Noonan Syndrome?

Noonan syndrome is caused by an abnormal mutation in a gene that is inherited from a parent. It is autosomal dominant meaning that the gene can be inherited from just one parent with the mutation. There are many genes that can be mutated (up to eight) but the syndrome can exist with any one of eight mutations.

What are the symptoms of Noonan Syndrome?

Symptoms vary from patient to patient but the commonest characteristic symptoms of noonan syndrome include unusual facial features, congenital heart defects and presence of a short stature. The heart defects that are present include at least one of the following: septal defect, hypertrophic cardiomyopathy and/or pulmonary stenosis. There tends to be learning difficulties, issues with behaviour and feeding amongst many other widespread problems such as reduced muscle tone, infertility and lymphedema (excess fluid in lymphatic system).

How is Noonan Syndrome treated?

There is no cure for noonan syndrome. Various aspects of the disorder can be treated such as correction of the congenital heart defects – this may be done through surgery or with medications. Regular check-ups will monitor progress and if needed, treatment and therapy will be provided at the relevant time (e.g. hormones to encourage growth). Specialist services such as speech and language therapist will be available as well as support groups.

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