Since this could suggest either a “driver” or a “passenger” role for APOBEC/ADAR mutations in cancer hypermutation, the burden of genomic variants was assessed in exomes with nonsynonymous versus synonymous APOBEC/ADAR mutations to check their true driver impact, showing that mutations in A1, A3B, A3C, and ADAR are correlated with indel variants, while ADARB1 mutations are correlated with certain SNVs. This evidence concerns the gene ADARB1 and cancer.