Diabetes, Vol 49, Issue 7 1269-1272, Copyright © 2000 by American Diabetes Association
A new mitochondrial DNA mutation at 14577 T/C is probably a major pathogenic mutation for maternally inherited type 2 diabetes
M Tawata, JI Hayashi, K Isobe, E Ohkubo, M Ohtaka, J Chen, K Aida and T Onaya
Third Department of Internal Medicine, Yamanashi Medical University, Tamaho, Japan. tawatam@res.yamanashi-med.ac.jp
From a family of 16 diabetic patients with typical maternal inheritance, we
investigated a 69-year-old woman with type 2 diabetes. The proband showed
no major deletions in the mitochondrial DNA (mtDNA). Direct sequencing
revealed 7 missense and 5 ribosomal RNA homoplasmic nucleotide
substitutions when compared with the Cambridge Sequence and its recent
revision. When compared with the control cybrid cells, the proband cybrid
cells showed 6 nucleotide substitutions. Among these, 14577 T/C, which
turned out to be 98.9% heteroplasmic, is a new missense substitution in the
NADH dehydrogenase 6 gene. We also observed 2 other patients with 14577 T/C
substitution from another group of 252 unrelated diabetic patients, whereas
no individual from a group of 529 control subjects had 14577 T/C
substitution. Furthermore, these 6 substitutions were in linkage
disequilibrium. Mitochondrial respiratory chain complex I activity and O2
consumption rates of the proband cybrid cells, which were obtained by the
fusion of mtDNA-deleted (rho0) HeLa cells and mtDNA from the proband,
showed 64.5 and 61.5% reductions, respectively, compared with control
cybrid cells. The present study strongly indicates that the new mtDNA
mutation at 14577 T/C is probably a major pathogenic mutation for type 2
diabetes in this family.