AD patient brains have shown hypertrophic astrocytes clustering around amyloid plaques (Duffy et al., 1980), upregulation of astrogliotic marker GFAP in brain homogenates (Meda et al., 2001), and elevated levels of GFAP in the CSF of AD patients (Fukuyama et al., 2001). The gene discussed is GFAP; the disease is Alzheimer disease.