Familial cerebral cavernous malformations (FCCM) is a disorder characterized by multiple vascular lesions in the brain and spinal cord that consist of clustered, endothelial-lined caverns ranging in diameter from a few millimeters to several centimeters. Cerebral and/or spinal cavernous malformations may increase in number over time, and individual lesions may increase or decrease in size. The number of cerebral cavernous malformations (CCMs) identified in an individual ranges from one or two to hundreds of lesions (typical number 6-20 CCMs) depending on the individual's age and the quality and type of brain imaging used. Although CCMs have been reported in infants and children, the majority become evident between the second and fifth decades of life either incidentally or associated with seizures, focal neurologic deficits, headaches, and/or cerebral hemorrhage. Cutaneous vascular lesions are found in 9% and retinal vascular lesions in almost 5% of affected individuals. Up to 50% of individuals with FCCM remain symptom free throughout their lives. [from GeneReviews]