The milder phenotype observed in patient-iPSC- and ESCp.(Ile98Ser)-derived β cells might indicate that the YIPF5 protein harboring the p.(Ile98Ser) mutation still maintains some residual activity, which is consistent with the 2 patients being diagnosed with diabetes in early infancy (rather than at birth) and having low but measurable C-peptide levels more than 10 years after diabetes diagnosis (Table 1). This evidence concerns the gene YIPF5 and diabetes mellitus.