Mitochondrial gene mutations that affect the binding of the termination factor and their prevalence among Japanese diabetes mellitus.
An A-to-G mutation at np3243 in tRNA(Leu) (UUR) gene of the mitochondrial DNA has been described to associate with diabetes mellitus. This exists within the sequence that is important for binding termination factor, which ends the transcription of one of the two major transcripts. We investigated the prevalence of this mutation in randomly selected 276 NIDDM+ 24 IGT, 94 IDDM, and 115 non-diabetic control subjects. The mutation was also reported to exist frequently in slowly progressive IDDM. We recruited 116 juvenile onset autoimmune Type 1 diabetes and 154 autoimmune thyroid diseases to see if this mutation is involved in autoimmunity. We identified this mutation in 3 of 300 NIDDM+IGT (1%). None from IDDM or control group, nor from autoimmune disease group had this mutation. The patients with this mutation did not have cerebro-muscular symptoms as were observed in MELAS. One patient had only slight glucose intolerance indicating diabetes with this mutation may have various phenotypes. Genetic area around tRNA(Leu) (UUR) is a hot spot for pathological mutations. We directly sequenced this area of mtDNA from diabetes and identified a new polymorphism in ND-1 gene, which is situated downstream of tRNALeu (UUR) gene. We screened 154 IDDM and 254 NIDDM+ IGT patients, and identified it in 3 NIDDM and 2 IGT subjects. Both of the NIDDM patients had bilateral hearing impairment. None from 207 non-diabetic control subjects and IDDM were positive for this mutation. Its prevalence was a little more than that of an A-G mutation at np3243.
Odawara
M
M
Department of Endocrinology and Metabolism, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
Asano
M
M
Yamashita
K
K
D016022:Case-Control Studies; D004272:DNA, Mitochondrial / Q000235:genetics* / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000235:genetics* / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000235:genetics / Q000378:metabolism; D005951:Glucose Tolerance Test; D006312:Hearing Loss, Bilateral / Q000150:complications / Q000235:genetics; D006801:Humans; D007564:Japan; D010454:Peptide Termination Factors / Q000378:metabolism*; D017354:Point Mutation; D012356:RNA, Transfer, Leu / Q000235:genetics; D013967:Thyroiditis, Autoimmune / Q000235:genetics / Q000378:metabolism
D004272:DNA, Mitochondrial; D010454:Peptide Termination Factors; D012356:RNA, Transfer, Leu