PIK3CA somatic mutations have been found in various overgrowth disorders, such as megalencephaly-capillary malformation syndrome, muscular hemihypertrophy, Klippel-Trenaunay syndrome, and CLOVES syndrome.20, 21, 22 The presenting phenotype of the PROS disorders seems to depend on the timing of the somatic mutation, the tissue localization of the mutations, and the location of the mutation in the embryo. This evidence concerns the gene PIK3CA and Klippel-Trénaunay syndrome.