Polymorphism of the Hepatocyte Nuclear Factor-1alpha Gene in the Early-onset of Type 2 Diabetes Mellitus with a Strong Family History in Korea

Kang, Eun Seok; Lee, Si Hoon; Zhao, Zheng Shan; Ahn, Chul Woo; Cha, Bong Soo; Lim, Sung Kil; Kim, Kyung Rae; Lee, Hyun Chul; Huh, Kab Bum; Ahn, Young Soo

Abstract

BACKGROUND: Maturity-onset diabetes of the young (MODY) is a genetically heterogenous subtype of type 2 diabetes characterized by an early onset, usually before 25 years of age, autosomal dominant inheritance and a primary defect in insulin secretion. Mutation of the hepatocyte nuclear factor-1alpha (HNF-1alpha) gene is known to be a cause of MODY3. This study was carried out to reveal whether HNF-1alpha gene polymorphism is a common cause of early-onset type 2 diabetes and MODY in the Korean population.
METHODS
Members of 12 pedigrees families with MODY and early-onset of type 2 diabetes were selected for the mutation detection. All of the families involved had at least two members with type 2 diabetes diagnosed before the age of 40 years, where the diabetes was inherited as an autosomal dominant trait, with at least 3 generations of diabetic subjects. Genomic DNA was extracted from whole- blood samples. The 10 exons and the promotor of the HNF-1alpha gene were sequenced.
RESULTS
In codon 17 of exon 1, 2 of the 10 control subjects and 5 of the 12 patients had nucleotide replacement where the CTC nucleotide was replaced by the CTG (p=0.381). This is a silent mutation where both the CTC and CTG code have the same amino acid leucine. In codon 27 of exon 1, 5 patients had a silent mutation, where the codon ATC is replaced by CTC and the amino acid changes from isoleucine to leucine, but no mutation was found in the control group (p=0.040). In codon 459 of exon 7, 2 of the controls and 3 of the patient group had a silent mutation (CTG -> TTG) that were both codon code leucine (p=1.000). Another missense mutation was observed in codon 487 of exon 7. Nucleotide AGC (serine) was replaced by AAC (asparagines). This mutation was observed in 5 control subjects and 10 patients (p=0.172).
CONCLUSION
This study did not reveal a new HNF-1alpha gene polymorphism. We conclude that the HNF-1alpha gene polymorphism does not play a major role in the early-onset of type 2 diabetes with a strong family history in Korea.