GFAP and amyotrophic lateral sclerosis: However while cortical astrogliosis is a feature of ALS [41], consistent with a previous study [77] there was no obvious perivascular pTDP-43 pathology suggestive of astrogliopathy and using pTDP-43-GFAP double labelling we were unable to find any clear evidence of pTDP-43 aggregates within GFAP+ astrocytes themselves (Fig. 6q-u).