RASA1 and cutaneous mastocytosis: The pathogenic RASA1 c.1583A>G (p.Y528C) missense variant was located within the pleckstrin homology domain and was previously identified as a mutation in a family with CM–AVM.3 The population frequency of the variant is <0.1% in 1000 Genomes (5/5,003 alleles) and ESP (4/13,006 alleles) databases.