HNF1A and diabetes mellitus: HNF1α and HNF1β form homodimers and heterodimers to regulate gene transcription in liver, pancreas, and kidney (Lau et al., 2018) and HNF1β mutations in MODY5 patients leads to severe diabetes (Horikawa, 2018), in part due to the fundamental role of HNF1β in early pancreatic morphogenesis (De Vas et al., 2015; El-Khairi and Vallier, 2016).