is a benign, highly vascular tumor that can occur in the brain, spinal cord, and retina (the light-sensitive tissue that lines the back of the eye). This tumor accounts for about 2% of brain tumors. As it enlarges, it presses on the brain and can cause neurological symptoms, such as headaches, weakness, sensory loss, balance and coordination problems, and/or hydrocephalus (a buildup of spinal fluid in the brain). Most hemangioblastomas occur sporadically. However, some people develop hemangioblastomas as part of a genetic syndrome called von Hippel-Lindau syndrome. These people usually develop multiple tumors within the brain and spinal cord over their lifetime. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.