As expected, levels of both total and phosphorylated tau protein are not specifically related to CAA and were marginally elevated in CSF from patients with CAA compared with controls, but were substantially lower than in patients with AD.50 51 54 Total tau protein levels are increased in CAA-ri, but both normal and increased levels of phosphorylated tau proteins have been described.51 53 54 These minor elevations in CSF tau protein levels are probably attributable to a low level of concomitant AD pathology (neurofibrillary tangles) in patients with CAA. The gene discussed is MAPT; the disease is Alzheimer disease.