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Health condition

Noonan syndrome in adults

Noonan syndrome - the most common RASopathy - carries into adulthood with cardiac surveillance (pulmonary valve and hypertrophic cardiomyopathy), bleeding tendency checks before surgery, lymphatic issues and fertility considerations.

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against current NHS and UK specialist society guidance at the time of review.

  • 03

    Current for 2026

    Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.

Key facts

The essentials at a glance.

Which gene and test confirm it, who should be tested in the family, and which specialist to see.

  • Caused by variants in RAS-MAPK pathway genes - PTPN11 most commonly, also SOS1, RAF1, RIT1 and others; autosomal dominant, though many cases are new mutations

  • Cardiac follow-up is lifelong: pulmonary stenosis may need reintervention decades after childhood repair, and hypertrophic cardiomyopathy (especially RAF1/RIT1) can emerge or progress in adulthood

  • Bleeding tendency affects up to half - coagulation screening belongs before every operation or dental extraction

  • Adults may also face lymphoedema, keloid scarring, undertreated hearing loss - and men frequently have reduced fertility after undescended testes

Understanding the condition

What it is and what happens next.

What causes it, how it is confirmed, and the testing and specialist routes available in the UK.

What it is and how it presents

Many adults with Noonan syndrome were diagnosed clinically as children - the distinctive facial features soften with age - and discharged from follow-up once a pulmonary valve was treated, leaving adulthood's questions unowned: valves restenose, cardiomyopathy can declare itself late, and an unrecognised factor deficiency turns routine surgery into a bleeding problem that a simple pre-operative screen would have predicted. Modern gene panels now also settle diagnoses that childhood medicine could only assert, and distinguish Noonan from its RASopathy neighbours.

Testing, surveillance and specialist care

An adult framework is straightforward: echocardiography at intervals set by the lesion and genotype, ECG, coagulation work-up ahead of procedures, lymphatic and dermatological attention as needed, and genetic confirmation with counselling - each child of an affected adult has a 50% chance, and prenatal options exist. Specialist cardiology familiar with RASopathy hearts adds real value where cardiomyopathy is in play. NHS clinical genetics services carry some of the longest waits in the health service, often many months for a first appointment, whereas private genetic testing and a specialist review can typically be arranged within around two weeks.

Seeing a specialist

Who to see, and how quickly you can be seen.

The specialist for this condition is usually a cardiologist working with clinical genetics. Your GP can refer you on the NHS, or you can arrange a private consultation directly.

A quiet reminder

This guide is for information, not medical advice.

Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any emergency symptoms.

Frequently asked

Common questions about Noonan syndrome in adults.

Quick, plain-English answers to what people ask us most.

  • What is Noonan syndrome in adults?

    Noonan syndrome is a genetic condition present from birth causing distinctive facial features, short stature, and often heart defects, with adults living with the condition needing ongoing monitoring for associated health issues throughout life.

  • What causes Noonan syndrome?

    It's caused by mutations in one of several genes involved in a specific cell signalling pathway, most commonly inherited in an autosomal dominant pattern, though many cases arise from a new mutation without a family history.

  • What health issues do adults with Noonan syndrome need to monitor?

    Adults need ongoing monitoring for heart conditions such as valve problems or hypertrophic cardiomyopathy, bleeding tendencies, and sometimes lymphatic or fertility issues, alongside general health maintenance.

  • Is Noonan syndrome hereditary?

    Yes, it's a genetic condition, most commonly inherited in an autosomal dominant pattern, meaning an affected parent has a 50 percent chance of passing it to each child, though many cases are new mutations.

  • Can Noonan syndrome be cured?

    There's no cure since it's a genetic condition present from birth, but individual features such as heart defects can be treated, and ongoing specialist monitoring helps manage associated health risks effectively.

  • How is Noonan syndrome managed in adulthood?

    Management involves regular cardiac monitoring, awareness of bleeding risk before any surgery or dental procedures, and coordinated specialist care addressing the specific features present in each individual.

  • When should an adult with Noonan syndrome seek specialist review, and how quickly can this be arranged privately?

    Seek regular specialist cardiology and genetics review, and promptly for any new symptoms. A private specialist can typically arrange assessment within about two weeks.