So far, only Endoglin (ENG), activin A receptor type II-like 1 (ACVRL1), Mothers against decapentapledic homolog 4 (SMAD4), and RAS activator 1 (RASA1) were reported to be causal genes of PAVMs and CM-AVMs [7-11]. Here, ACVRL1 is linked to cutaneous mastocytosis.