Missense mutations in the human insulin promoter factor-1 gene are not a common cause of Type 2 diabetes mellitus in Taiwan

Type 2 diabetes mellitus (T2DM) is a common metabolic disorder characterized by a hyperglycemia resulting from defect in insulin secretion and insulin action. Recent studies showed that dominant negative mutations in the insulin promoter factor-1 (IPF-1), a pancreatic β-cell specific transcription factor, cause maturity-onset diabetes of the young (MODY), a subtype of T2DM with early onset and monogenic autosomal inheritance. In addition to MODY, IPF-1 mutations are suggested to predispose to common late-onset T2DM with different penetration of the mutations reflected in their in vitro activity. Thus, we investigated IPF-1 C18R, Q59L, D76N and R197H mutations in Taiwanese patients with common late-onset T2DM, because research into IPF-1 variants in Taiwanese diabetic patients - a population with the lowest range of diabetic incidence - has never been documented. Peripheral blood samples were collected and genomic DNA was extracted from 434 patients with T2DM and 194 non-diabetes control study subjects. IPF-1 genetic variations were analyzed by PCR and restriction fragment length polymorphism (RFLP) analysis. We did not find any of these four IPF-1 mutations in our patients. Our results suggested that IPF-1 mutations were not a common cause associated with Taiwanese T2DM.