The recent discoveries of somatic mutations in the guanine nucleotide-binding protein, G alpha subunit q (GNAQ) (R183Q), phosphatidylinositol 3-kinase (PI3K) and activation of mitogen-activated protein kinase (MAPK) and PI3K pathways in skin lesions of PWS/SWS have greatly enhanced our understanding of the pathogenesis of the malformations [7,8,9,10]. The gene discussed is PIK3CA; the disease is Sturge-Weber syndrome.