Sturge-Weber syndrome (SWS) is the association of the facial port-wine birthmark with malformed leptomeningeal blood vessels and abnormal venous eye vessels. Occurrence is sporadic and in both males and females and reported in all racial and ethnic backgrounds. The genetic cause accounting for SWS is a somatic mosaic mutation in the GNAQ gene encoding the Gαq protein. Testing for this somatic mosaic mutation may be useful in the future for differentiating a SWS diagnosis in these patients from other capillary malformation related syndromes, such as -megalencephaly-capillary malformation-polymicrogyria syndrome, which also have capillary malformations but are otherwise different in terms of prognosis and associated complications. With the discovery of the causative somatic mosaic mutation, current SWS research will likely result in new in vitro and animal models, potential novel treatment strategies, and new insights into the pathophysiology of this vascular malformation disorder.