EPHB4 Mutation Implicated in Capillary Malformation-Arteriovenous Malformation Syndrome: A Case Report.

Capillary malformation-arteriovenous malformation (CM-AVM) syndrome, due to inactivating mutations in RASA1 in 68% of cases, is characterized by the development of cutaneous capillary malformations and arteriovenous malformations or fistulas; no known genetic etiology has been identified in patients with CM-AVM syndrome without RASA1 mutations. We present the case of a child with RASA1-negative CM-AVM syndrome with a de novo missense mutation in EPHB4, a transmembrane tyrosine kinase receptor essential for vasculogenesis. Inactivating the mutation in EPHB4 has been shown to upregulate the mitogen-activated protein kinase pathway and the mammalian target of rapamycin complex 1, possibly contributing to the development of vascular malformations.