Klippel–Trenaunay and Sturge–Weber Overlap Syndrome with KRAS and GNAQ mutations

Patients with combined phenotypes of Sturge–Weber syndrome and Klippel–Trenaunay syndrome have been reported, though the underlying genetic spectrum in these individuals remains to be elucidated. We reported the patient presenting with Klippel–Trenaunay and Sturge–Weber overlap syndrome in mainland China. Histopathologic study confirmed the hemangioma of vein and capillary. Co‐existence of a novel somatic KRAS c.182_183 delins TC mutation and GNAQ c.548G>A mutation was identified in the affected skin tissue rather than paired peripheral blood. The somatic mutations of GNAQ and KRAS may affect MAPK‐ERK signaling pathway, resulting in endothelial anomaly and blood vessel malformation.