Systemic Vasculopathy Associated With Homozygous <i>RNF213</i> Mutation Presenting as Peripheral Pulmonary Artery Stenosis and Coronary Vasospasm Without Moyamoya Disease: A Case Report

We report the case of a 19-year-old man who presented with exertional dyspnea and recurrent chest pain, with a homozygous mutation in the <i>RNF213</i> gene and without evidence of moyamoya disease. Coronary angiography revealed significant stenosis in the left main coronary artery and ergonovine provocation testing demonstrated severe vasospasm, leading to a diagnosis of variant angina. Intravascular ultrasound revealed fibrous intimal thickening without atherosclerotic plaque. Pulmonary artery angiography revealed multiple segmental stenoses with a beaded appearance, suggestive of peripheral pulmonary artery stenosis. Right heart catheterization confirmed pre-capillary pulmonary hypertension. The patient underwent percutaneous coronary intervention for the coronary lesion, followed by balloon pulmonary angioplasty, resulting in marked improvement in symptoms, right ventricular function, and pulmonary hemodynamics. Genetic testing confirmed a homozygous <i>RNF213</i> p.R4810K (c.14429G>A) mutation. This case highlights the systemic vascular involvement associated with <i>RNF213</i> mutations, even in the absence of moyamoya disease, and underscores the importance of comprehensive vascular evaluation in young patients presenting with unexplained coronary and pulmonary artery abnormalities.