Mutations inAP5Z1, a gene playing a role in intracellular membrane trafficking, have been reported to be associated with SPG48 with a diverse spectrum of movement disorders, including ataxia, myoclonus, spasticity, dystonia, and parkinsonism.33Although not an SPG, the adult form of Alexander's disease should be included in the differential diagnosis. Here, AP5Z1 is linked to hereditary spastic paraplegia.