Mutations in Hepatocyte Nuclear Factor-la in Early-Onset Type 2 Diabetes Mellitus in Korea

Kim, Kyoung Ah; Lee, Myung Shik; Ahn, Kyu Jeung; Chung, Jae Hoon; Min, Yong Ki; Lee, Moon Kyu; Lee, Ki Up; Kim, Ghi Su; Suk, Kyoung Ho; Hwang, Dae Yeun; Kim, Kwang Won

Abstract

BACKGROUND: Type 2 diabetes mellitus is a heterogeneous disorder caused by the unfavorable combination of genetic and environmental factors. Maturity-onset diabetes of the young (MODY) is a rare form of familial type 2 diabetes mellitus characterized by an early onset, and it is appearance in at least three consecutive generations, consistent with an autosomal dominant mode of inheritance. It accounts for 1~3% of type 2 diabetes mellitus cases. As of today, five different MODY genes have been identified. In 1996, Yamagata et al. reported that MODY3 and MODY 1 were caused by mutations in hepatocyte nuclear factor (HNF) la and 4a, respectively. Furthermore, there have been reports that HNF-la gene mutation could be a cause of early-onset type 2 diabetes mellitus with familial history, although these patients do not fulfill the clinical criteria of MODY. Therefore, the purpose of this study was to examine the mutation of HNF-la gene in early-onset type 2 diabetes mellitus in Korean subjects. METHODS: Sixteen cases of early-onset type 2 diabetes mellitus with familial history were included in the study. Five of these subjects were MODY patients according to our revised criteria. DNA was isolated from peripheral blood. The 10 exons and flanking introns of the HNF-1 a gene were amplified by polymerase chain reaction (PCR). The PCR products were sequenced using an AmpliTaq FS Dye Terminator Cycle Sequencing Kit (Perkin-Elmer Applied Biosystems). RESULT: Mutation in the HNF-la gene was identified in 1 of the 16 patients. It was a hitherto unreported novel missense mutation, R263L. This mutation co-segregated with type 2 diabetes mellitus or impaired glucose tolerance in his family and was not found in family members with normal glucose tolerance. CONCLUSION: Findings from this study suggests that MODY3 caused by mutation of HNF-la gene is also present in early onset type 2 diabetic of Korean subjects. This is the first time that HNF-la mutation causing MODY was identified in Korea.