We first examined variants in the 13 known MODY or neonatal diabetes genes, five of which (HNF1A, GCK, ABCC8, INS, and KLF11) were associated with increased risk of youth-onset T2D at nominal significance (P < 0.05) in ProDiGY (Supplementary Table 20). This evidence concerns the gene GCK and type 2 diabetes mellitus.