Screening for MODY Mutations, GAD Antibodies, and Type 1 Diabetes– Associated HLA Genotypes in Women With Gestational Diabetes Mellitus

OBJECTIVE: To investigate whether genetic susceptibility to type 1 diabetes or maturity-onset diabetes of the young (MODY) increases susceptibility to gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: We studied mutations in MODY1-4 genes, the presence of GAD antibodies, and HLA DQB1 risk genotypes in 66 Swedish women with GDM and a family history of diabetes. An oral glucose tolerance test was repeated in 46 women at 1 year postpartum. RESULTS: There was no increase in type 1 diabetes-associated HLA-DQB1 alleles or GAD antibodies when compared with a group of type 2 diabetic patients (n = 82) or healthy control subjects (n = 86). Mutations in known MODY genes were identified in 3 of the 66 subjects (1 MODY2, 1 MODY3, and 1 MODY4). Of the 46 GDM subjects, 2 had diabetes (4%) and 17 had impaired glucose tolerance (IGT) (37%) at 1 year postpartum. Of the two subjects who developed manifest diabetes, one carried a MODY3 mutation (A203H in the hepatocyte nuclear factor-1alpha gene). There was no increase in high-risk HLA alleles or GAD antibodies in the women who had manifest diabetes or IGT at 1 year postpartum. CONCLUSIONS: MODY mutations but not autoimmunity contribute to GDM in Swedish women with a family history of diabetes and increase the risk of subsequent diabetes.