CASP6 and Alexander disease: As mentioned above, Battaglia et al. recently used Alexander disease (AxD) patient brain tissue and induced pluripotent stem cell (iPSC)-derived astrocytes to identify that AxD-causing mutations lead to selective phosphorylation of GFAP at Ser13 and subsequent GFAP cleavage by caspase-6 and cytoplasmic aggregation formation in patients who died young [51].