In addition, certain HLA alleles associated with T1D [54,55,56] and common polymorphism of the maturity-onset diabetes of the young (MODY) genes, such as GCK (MODY2 gene) and HNF1A (MODY3 gene), have been reported to associate with GDM [57,58]. The gene discussed is HNF1A; the disease is gestational diabetes.