MUTATION IN THE MITOCHONDRIAL TRNA(LEU) AT POSITION-3243 AND SPONTANEOUS-ABORTIONS IN JAPANESE WOMEN ATTENDING A CLINIC FOR DIABETIC PREGNANCIES

Mitochondrial DNA is exclusively maternally inherited. We recently fou nd the prevalence of diabetic patients with an A to G transition at po sition 3243 of leucine tRNA (3243 base pair (bp) mutation) to be nearl y 1 % in randomly selected Japanese subjects. Here, we report the high er prevalence of diabetic patients with the 3243 bp mutation in a spec ific Japanese population of women attending a diabetic pregnancy clini c. Of 102 patients with non-insulin-dependent diabetes mellitus 6 (5.9 %) were positive for the mutation, 1 (8.3 %) of 12 patients with gest ational diabetes and 2 (5.9 %) out of 34 borderline diabetic patients. In contrast, none of 64 patients (0 %) with insulin-dependent diabete s mellitus had the 3243 bp mutation. Moreover, there was a difference in the prevalence of spontaneous abortions between patients with and w ithout this mutation (27.3 vs 12.4 %). Among nine probands with the mu tation, four had a history of one spontaneous abortion (p = 0.0518) an d two had a history of two abortions (p = 0.0479). Two probands had a spontaneous abortion even while under strict diabetic metabolic contro l. The 3243 bp mutation thus may cause spontaneous abortion during pre gnancy.