ZFYVE26 and hereditary spastic paraplegia: Another common manifestation are hereditary spastic paraplegias: SPG11- and ZFYVE26-related HSPP share signs of early-onset spasticity, frequently with a consistent combination of features (referred to as “Kjellin syndrome”) comprising intellectual impairment, pigmentary retinopathy, cerebellar dysfunction and, variably, parkinsonism.