Carbonic Anhydrase 8 (CA8) belongs to the alpha-carbonic anhydrase family. Alpha-carbonic anhydrase is a large family of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide. Because CA8 has some sequence similarity with other known carbonic anhydrase genes, it was firstly called as CA-related protein. Nevertheless, CA8 does not have a carbonic anhydrase catalytic activity. Defects in CA8 are the cause of cerebellar ataxia mental retardation and dysequilibrium syndrome type 3 (CMARQ3), which is a congenital cerebellar ataxia associated with dysarthia, quadrupedal gait and mild mental retardation.