It should be mentioned here that rat Tcf7l2, and the exclusively pancreatic islet expressed Slc30a8, whose variants confer both diabetes risk and protective effects [46] and whose autoantibodies are detected in T1D patients [66], have targeted mutations introduced via zinc finger nuclease (ZFN) mutagenesis. The gene discussed is TCF7L2; the disease is type 1 diabetes mellitus.