Combined with the result that GCK‐MODY probands were about 0.87 years younger at recruitment compared to those with HNF1A‐MODY (Supplementary Figure S49 in Appendix S1), we speculate that there may be no actual difference in age at diagnosis of diabetes between patients with GCK‐MODY and those with HNF1A‐MODY. The gene discussed is HNF1A; the disease is diabetes mellitus.