Sturge-Weber syndrome (SWS) is a neurocutaneous disorder that presents with a facial port-wine stain and a leptomeningeal angioma. Fibronectin expression regulates angiogenesis and vasculogenesis and participates in brain tissue responses to ischemia and seizures. We therefore hypothesized that abnormal gene expression of fibronectin and other extracellular matrix genes would be found in SWS brain tissue and SWS port-wine skin fibroblasts. Fibronectin gene and protein expression from port-wine-derived fibroblasts were compared with that from normal skin-derived fibroblasts of four individuals with SWS using microarrays, reverse transcriptase-PCR, Western analysis, and immunocytochemistry. Fibronectin gene and/or protein expression from eight SWS surgical brain samples was compared with that in two surgical epilepsy brain samples and six postmortem brain samples using microarrays, reverse transcriptase-PCR, and Western analysis. The gene expression of fibronectin was significantly increased (p Ͻ 0.05) in the SWS port-wine-derived fibroblasts compared with that of fibroblasts from SWS normal skin. A trend for increased protein levels of fibronectin in port-wine fibroblasts was found by Western analysis. No difference in the pattern of fibronectin staining was detected. The gene expression of fibronectin was significantly increased (p Ͻ 0.05), and a trend for increased fibronectin protein expression was found in the SWS surgical brain samples compared with the postmortem controls. These results suggest a potential role for fibronectin in the pathogenesis of SWS and in the brain's response to chronic ischemic injury in SWS. The reproducible differences in fibronectin gene expression between the SWS port-wine-derived fibroblasts and the SWS normal skin-derived fibroblasts are consistent with the presence of a hypothesized somatic mutation underlying SWS. Sturge-Weber syndrome (SWS) is a neurocutaneous disorder that classically presents with a facial port-wine stain, in the ophthalmic distribution of the trigeminal nerve, associated with an ipsilateral leptomeningeal angioma. Children and adults with SWS often develop progressive neurologic problems, including difficult-to-control seizures, migraines, stroke-like episodes, mental retardation, and hemiparesis. Treatment for SWS is largely symptomatic and directed at the control of seizures with anticonvulsants or surgery (1, 2). SWS occurs almost entirely sporadically and with equal frequency in the sexes (3). The genetic or environmental/ prenatal factors resulting in the disorder are not known. The localized abnormalities of blood vessel development and function affecting the facial skin, eye, and brain suggests a developmental disruption that occurs in the first trimester of pregnancy (4). Somatic mutation has been cited as the probable cause of SWS, given the localized, asymmetric abnormality of blood vessel formation (5). However, the putative mutation is unknown, and other molecular mechanisms are possible. No animal model for SWS exists at this time.Histologic s...