GFAP and Alexander disease: A key histopathological feature of all forms of AxD is the widespread deposition of inclusion bodies within astrocytes known as Rosenthal fibers, consisting of aggregated GFAP, the small stress proteins HSP27 and αB-crystallin (Tomokane et al., 1991; Head et al., 1993; Iwaki et al., 1993) and likely other unidentified proteins.