Mitochondrial aldehyde dehydrogenase in diabetes associated with mitochondrial tRNA(Leu(UUR)) mutation at position...

To ascertain why alcohol is prone to manifest unpleasant effects in diabetes associated with mitochondrial tRNA(Leu(UUR) mutation at position 3243 (DM-Mt3243), we investigated the genotype of aldehyde dehydrogenase (ALDH) 2 and alcohol dehydrogenase 2 (ADH2) in DM-Mt3243.

Nineteen unrelated patients with DM-Mt3243 were included in the study (12 men and 7 women). They were recruited from approximately 700 diabetic patients at three different institutes, without prior information of alcohol habit. ALDH2, ADH2, and 3243 mutation were genotyped by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) methods. There were 461 unrelated Japanese individuals and 170 non-3243 mutant NIDDM patients enrolled as control subjects.

In the DM-Mt3243 group, 15 (79%) patients had inactive ALDH2 and 18 (95%) had atypical ADH2. The frequency of the inactive ALDH2 genotype was higher than that in the normal control subjects (P < 0.002) and that in the NIDDM control subjects (P < 0.003). However, the frequencies of ADH2 genotype in the DM-Mt3243 group, the normal control subjects, and the NIDDM control subjects were not different.

Inactive ALDH2 genotype was frequently observed in DM-Mt3243. It suggests that DM-Mt3243 is associated with ALDH2 inactivity. We speculate the trait of acetaldehyde accumulation on ALDH2 inactivity may favor mitochondrial DNA abnormalities, thereby worsening ATP production and impairing insulin secretion. In addition, the interaction of ALDH1 and ALDH2 may alter the retinoid metabolism in the pancreas, thereby influencing insulin secretion and precipitating diabetes. Thus, this association of ALDH2 genotype with DM-Mt3243 provides insight into the etiology of diabetes in the mitochondrial diseases.