The effects of GFAP overexpression were investigated in transgenic mice carrying human genomic clones of the GFAP gene resulting in GFAP overexpression.104 The engineered mice presented hypertrophic astrocytes with intracellular intermediate filaments aggregates and inclusion bodies identical to Rosenthal fibres found in Alexander’s disease.105,106 GFAP overexpression, while essential for promoting tissue repair and containing damage in the CNS, can also lead to the formation of glial scars and disruption of neural circuits, ultimately contributing to cognitive decline. Here, GFAP is linked to Alexander disease.