Search for mitochondrial DNA mutation at position 3243 in German patients with a positive family history of maternal diabetes mellitus.

Mitochondrial diabetes is one of the most common monogenetic forms of diabetes mellitus. However, variable prevalences have been reported by different investigators. Therefore, the aim of our study was to investigate the prevalence of the most prevalent mitochondrial DNA mutation at position 3243 (A --> G) in german patients with a positive family history of maternally inherited diabetes mellitus and/or hearing loss. We screened 1460 patients with diabetes mellitus by a questionnaire and identified 122 patients with a positive family history of maternal diabetes mellitus. Seven of the 122 patients suffered from hearing loss in addition. An EDTA blood sample of each patient was examined by polymerase chain reaction followed by a digestion with Bsp120I. In addition all samples were further examined by denaturing gradient gel electrophoresis to increase the detection limit for heteroplasmy. Only one mt DNA mutation at position 3243 could be detected in the 122 patients. The detection limit of denaturing gradient gel electrophoresis (DGGE) for heteroplasmy was 3%. We detected one new polymorphism at position 3333 (C --> T) of the mitochondrial genome (0.8% of the patients), and a known polymorphism at position 3197 (T --> C) in 10.6% of the patients. We therefore conclude that the frequency of the A3243G mutation is much lower in the investigated study population, mostly originating from Saxonia, than in asian populations.