FLT4 and capillary malformation-arteriovenous malformation 1: To address this shortcoming, contemporary classification systems are now incorporating genetic and phenotypic elements (Gordon et al., 2020), including conditions such as Parkes-Weber syndrome (associated with RASA1), lymphedema-distichiasis syndrome (FOXC2), Milroy disease (FLT4), and Emberger syndrome (GATA2).