What are the cardinal features of Noonan syndrome?

Noonan syndrome presents with short stature, congenital heart defect (pulmonary stenosis most common, also HCM), typical facies (hypertelorism, downslanting palpebral fissures, low-set ears), and bleeding tendency. PTPN11 mutations account for ~50%.

Which RASopathy gene should be tested first?

PTPN11 first for classical Noonan. If negative: SOS1, RAF1, RIT1, KRAS. RAF1 mutations specifically associate with HCM (occurs in ~70–75% vs ~20% overall). CFC features suggest BRAF, MAP2K1/2.

RASopathy (Noonan/LEOPARD/CFC Syndrome) Risk Assessment

Assess pre-test probability of RASopathy (Noonan syndrome, LEOPARD syndrome, Costello syndrome, cardiofaciocutaneous syndrome) based on phenotypic features and guide targeted gene panel selection.

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RASopathy (Noonan/LEOPARD/CFC Syndrome) Risk Assessment

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Frequently Asked Questions

What are the cardinal features of Noonan syndrome?

Which RASopathy gene should be tested first?