Genotype–Phenotype and Genotype–Outcome Analysis of Capillary Malformation–Arteriovenous Malformation

Capillary malformation-arteriovenous malformation syndrome (CM-AVM) is a rare autosomal-dominant complex vascular disorder that can be associated with fast-flow vascular malformations (FFVMs). The purpose of this study is to explore the genotype–phenotype and genotype–outcome associations based on a large parallel sequencing of CM-AVM patients to improve the understanding of the development and risk factors for FFVM. A total of 117 patients with CM-AVMs were enrolled in this multicenter cohort study. All patients underwent detailed clinical phenotyping, including age, sex, capillary malformation (CM) size, with or without FFVM, and outcome (Schobinger stage). Next-generation sequencing was performed with peripheral blood and tissue samples. Genotype–phenotype, genotype–outcome, and phenotype–outcome analyses were performed. Germline or mosaic RASA1 variants were the most common cause of CM-AVM, found in 61.5%, with EPHB4 variants in 32.5%. A total of 76.9% of patients had a dominant CM lesion larger than 5 cm. No obvious correlations between genotypes and phenotypes, including sex, age, location, and size of CMs, were found in this cohort. Comparing the patients with FFVMs with those without FFVMs, we found significant differences in age and the size of dominant CM lesions but not in genotype, sex, or location. CM-AVMs can be categorized as complex vascular malformations caused by different gene alterations in the RAS/RAF/MEK pathway. No obvious correlations between genotypes and phenotypes were identified. Critically, the occurrence and progression of FFVM is strongly determined by phenotypes, including age and the size of the dominant CM, rather than genotypes.