HNF1A and MODY: However, so far the only example of genetic predisposition to GDM is represented by maturity onset diabetes of the young (MODY), a clinically heterogeneous autosomal dominant monogenic disease, accounting for up to 5% of diabetes and due to mutations in different genes such as HNF4A, GCK, HNF1A, IPF1, HNF1B, and NEUROD1.