Under pathological conditions, such as reactive astrogliosis or Alexander disease (AxD), GFAP overexpression or mutation leads to formation of Rosental fibers (aggregates of ubiquitinated GFAPs, αB-crystallin, and heat shock protein 27) in astrocytes, filament disorganization, mitochondrial mislocalization, and impaired organelle crosstalk [48,57]. This evidence concerns the gene GFAP and Alexander disease.