Beyond the usual: coronary artery abnormalities in Noonan syndrome

Background. Noonan syndrome (NS) is a multisystemic genetic disorder primarily affecting the cardiovascular system. While pulmonary valve stenosis and hypertrophic cardiomyopathy are common cardiac manifestations, coronary artery anomalies (CAAs) are rare but potentially life-threatening complications. Case Presentation. A 12-year-old boy with genetically confirmed Noonan syndrome due to a PTPN11 mutation (p.Asn308Asp, c.922A>G) had been followed since infancy. He initially had mild pulmonary valve stenosis that regressed spontaneously. He received intermittent growth hormone therapy, which was discontinued for two years and restarted 1.5 years prior to presentation. Routine echocardiography revealed newly detected coronary artery ectasia involving the left main coronary artery (LMCA) and the left anterior descending (LAD) artery. Coronary computed tomography angiography confirmed ectatic dilation of the LMCA and LAD, with an intramyocardial course of the mid-LAD. Further evaluation with cardiopulmonary exercise testing, myocardial perfusion scintigraphy, and selective coronary angiography demonstrated normal myocardial perfusion, an absence of ischemia, and diffuse coronary ectasia without discrete aneurysm formation. The patient remained asymptomatic, and no flow-limiting lesions were identified. Conclusion. This case highlights a rare vascular manifestation of NS and underscores the importance of vigilant cardiovascular surveillance. Due to the rarity of such cases and the lack of standardized monitoring or treatment protocols, individualized risk stratification remains essential. Reporting such cases is critical for raising awareness and guiding future management strategies for coronary anomalies in Noonan syndrome.