In MACCS1, the five most frequently mutated genes were CTNNB1, TP53, TTN, MUC16, and CNTNAP5. By contrast, the mutational profile of MACCS2 was dominated by MUC16 and CMYA5. Although MUC16 or CMYA5 are not classic ACC drivers, their recurrent mutations in MACCS2 suggest functional contributions to tumor biology. The gene discussed is MUC16; the disease is neoplasm.