BACKGROUND: The influences of genetic and environmental factors form aclinical picture of type 2 diabetes mellitus. Genetic studies of type 2 diabetes mellitus become increasinglyimportant. The knowledge of the molecular background of type 2 diabetes has been growing rapidly overrecent years. One of the forms of the disease defined on the molecular level is maternally inheritedtype 2 diabetes mellitus. This diabetes, which is frequently accompanied by hearing impairment of deafness(maternally inherited diabetes with deafness-MIDD), was linked with sequence differences in mitochondrialDNA. The most frequent cause of MIDD is A3243G substitution in a mitochondrial tRNA(Leu) gene. Whilethis mutation was identified in different races in several populations, it is still important and valuableto evaluate its prevalence in various ethnic groups. The aim of the project was to determine the prevalenceof A3243G substitution in a mitochondrial tRNA(Leu) gene among Polish diabetic subjects.
MATERIAL ANDMETHODS: In total 129 individuals, with type 2 diabetes and 12 with gestational diabetes were selectedfor this study. Two techniques based on restriction fragment length polymorphism (RFLP) method were usedto screen for A3243G mutation. In the first approach, non-radioactive PCR reactions of mitochondrialDNA region of interest were performed using DNA of the study participants. This was followed by Apa Irestriction enzyme digestion of the PCR product. Subsequently an electrophoretic separation was doneon 2% agarose gel with ethidium bromide staining. In the second, more sensitive, modification of RFLP,[alpha 32P]dCTP was used for internal primer labeling and the electrophoresis was done on acrylamidegel. A positive sample was used to control the quality of the genotyping.
RESULTS: In both approachesnone of the samples, except for the positive control, showed the evidence of the G variant.
CONCLUSIONS:In summary, the A3243G mutation in mitochondrial tRNA(Leu) gene is not a frequent cause of diabetes inthe Polish population. Further screening of enlarging study group is necessary to fully determine theprevalence of this mutation in our population. This, together with the search for other mitochondrialmutations, should allow to fully determine the prevalence of MIDD and its specific molecular backgroundin the Polish population.

Keywords: Type 2 diabetes mellitus, Genetics, Mitochondrial, Mutation