Noonan syndrome is a genetic multisystem disorder characterised by distinctive facial features, developmental delay, learning diffi culties, short stature, congenital heart disease, renal anomalies, lymphatic malformations, and bleeding diffi culties. Mutations that cause Noonan syndrome alter genes encoding proteins with roles in the RAS-MAPK pathway, leading to pathway dysregulation. Management guidelines have been developed. Several clinically relevant genotype-phenotype correlations aid risk assessment and patient management. Increased understanding of the pathophysiology of the disease could help development of pharmacogenetic treatments.