Screening for Mitochondrial DNA Mutations of MELAS tRNA Leu(3243), MERRF tRNA Lys(8344) in Korean IDDM Patients

Yoo, Han Wook

Abstract

An A to G mutation at nucleotide 3243 or 8344 of the mitochondrial genome has been associated with insulin dependent diabetes mellitus(IDDM) and noninsulin dependent diabetes mellitus(NIDDM) in some patients whose family members are frequently affected in maternally inherited fashion. The hypothesis is entertained that defective oxidative phosphorylation system(OXPHOS) caused by mitochondrial DNA mutations would hamper the insulin secretion from pancreas beta islet cells, which requires large amount of ATP energy. Recently, a number of study have been reported to examine the frequecy of these mutations in diabetic populations. In this study, efforts have been directed to investigate the frequency of MELAS tRNALeu(3243) and MERRF tRNALys(8344) mutations in 53 Korean IDDM patients. Total genomic DNA extracted from patients' lymphocytes have been amplified using two sets of mitochondrial specific primers to cover the regions of nt 3243 or 8344. PCR-RFLP anlaysis using Apa I for MELAS(3243) or Ban II for MERRF(8344) were utilized to screen the presence of these mutations in 53 IDDM patients. Two positive controls have been directly sequenced to confirm the presence of these mutations. The results showed that none of IDDM patients(0/53) screened carried these mutations. In conclusion, mitochondrial DNA mutations of MELAS(3243) or MERRF(8344) may be very rare causative factor in developing IDDM, though a large number of IDDM patients are needed to be screened.