Carbonic anhydrase-related protein VIII (CA8) is an IP<sub>3</sub>R1-regulating protein abundantly expressed in cerebellar Purkinje cells and is a causative gene of congenital ataxia.
In addition, homozygous missense mutations in carbonic anhydrase-related protein VIII (CARP), which suppresses the ability of IP3 to bind to IP3R1, cause a recessively inherited ataxia with mild cognitive impairment with/without quadrupedal gait.
A mutation in the CA8 gene has been associated with ataxia, mild mental retardation and quadrupedal gait in humans and with lifelong gait disorder in mice, suggesting an important role for CARP VIII in the brain.