Many MODY-associated TF genes show incomplete penetrance, e.g., HNF1A, HNF1B, HNF4A, NEUROD1, PDX1, and RFX6 (Mirshahi et al., 2022; Li et al., 2023; Sharp et al., 2025; Sriram et al., 2025). Here, HNF4A is linked to MODY.