To then determine the direct targets of HNF1A that could be responsible for β cell dysfunction in our MODY3 patients with HNF1A+/H126D mutation, we performed ChIP-Seq analyses to compare targets bound by WT HNF1A versus H126D mutant protein in the differentiated endocrine progenitors. Here, HNF1A is linked to maturity-onset diabetes of the young type 3.