HNF1A and diabetes mellitus: The aims of the present study were: 1) to compare the disease progression of type 1 diabetes among children negative and children positive for ICA, GADA and IA-2A, (subsequently referred to as autoantibody negative and autoantibody positive) during the first 12 months after disease onset, and 2) to investigate whether mutations in the KCNJ11, ABCC8, HNF1A, HNF4A or INS genes are common in children and adolescents with AAB negative diabetes.