Interestingly, a mouse KO for type II PI4K, Pi4k2a, develops late-onset features resembling hereditary spastic paraplegia (HSP), with severe axonal degeneration in the spinal cord that is associated with tremors, high-frequency nodding, spastic gait, limb weakness and urinary incontinence (Simons et al., 2009). The gene discussed is PI4K2A; the disease is hereditary spastic paraplegia.