The cytotoxic effect of islet amyloid polypeptide (IAPP) misfolding and aggregation has a well-recognized role in the pathogenesis of type 2 diabetes mellitus, mediated by failure of the beta cell's protein quality control system to rescue the cell from overwhelming proteotoxic stress induced by IAPP aggregates, ultimately leading to apoptosis. The gene discussed is IAPP; the disease is diabetes mellitus.