Capillary Malformation-Arteriovenous Malformation Syndrome Associated with RASA1 and EPHB4 Mutations: Comparative Case Series and Narrative Review.

Capillary malformation-arteriovenous malformation syndrome is a rare spectrum of vascular anomalies characterized by capillary malformations and high-flow vascular malformations, caused by loss-of-function mutations in the RASA1 and/or EPHB4 genes. These mutations disrupt vascular differentiation and lead to complex malformations involving the brain, skin, and systemic vasculature. Since the first description in 2003, more than 200 cases have been reported, but intracranial arteriovenous shunts during the neonatal period remain extremely rare, as well as reports of the dual mutation RASA1 + EPHB4 or the immunological impact of the EPHB4 mutation. We report three cases of neonates presenting with early-onset high-flow shunts, each exhibiting a distinct genetic signature: CM-AVM1 (RASA1 mutation), CM-AVM2 (EPHB4 mutation), and dual variant (combined EPHB4 and RASA1 mutations). We analyzed and compared the clinical evolution, Doppler ultrasound trends, EEG, MRI and genetic data to highlight the distinct genotype-phenotype spectrum. Early multimodal hemodynamic evaluation of neonates with CM-AVM allows the identification and optimum management of life-threatening shunts at the earliest possible stage.