ATP8A2 and cerebellar ataxia: Mice deficient in ATP8A2 are smaller than their wild-type littermates, live only 1–2 months, exhibit severe neurological abnormalities including ataxia, body tremors, distal axonal degeneration of spinal neurons, and display sensory defects associated with reduced function and degeneration of photoreceptor cells and ganglion cells of the retina and spiral ganglion cells of the auditory system5,6.