An increasing number of allelic conditions have now been shown to have features of two different phenotypes in the same individual or family—the Janus (after the ancient Roman god with two faces) or dual phenotype.23,24 Furthermore, overlapping lymphatic and vascular features have previously been reported in patients with RASA1-associated CM-AVM type 1.25 This evidence concerns the gene RASA1 and cutaneous mastocytosis.