Thereis only one Adar gene in Drosophila,49 and it is an orthologue of human ADARB1 (ADAR2).50 Mutant flieslacking Adar activity are obtained in reduced numbers from crossesbecause some of the mutants die as larvae, Adar mutantflies have locomotion defects and ataxia and suffer from age-relatedneurodegeneration49 (Figure 4). This evidence concerns the gene ADAR and cerebellar ataxia.