Evaluation of the human mitochondrial DNA polymorphism analysed by using RFLP techniques

V SUMMARY As the molecular genetic techniques have been developed and become available, the sciences of biology and genetics have gained an acceleration. This molecular techniques are being used in a large scientific field like medicine, agriculture, biology and others. The use of molecular genetic, methods was now a must for the solution of problems in this scientific fields. The development of PCR methods has been a revolution in genetics, and it has been possible to replicate in vitro nucleotide sequences. After the caracterization of the first mitochondrial DNA linked disease (LHON) molecular genetic techniques were used to define several other diseases of which mitochodrial DNA takes part in the aethiopathogenese. It is proved that DNA sequence differences between individuals are not always a reason for a disease. These sequence differences have been fixed for populations. Moreover, being aware of the proportionally change of the DNA sequence in the course of time provides a way of evaluation for the evolution of the modern human being by using molecular genetic techniques. Differences among DNA sequences of healthy individuals indicated that molecular changes are not always an aethiological factor for clinical pathology. For this reason polymorphism studies were considered necessary. To prevent mistakes in clinical studies, the polymorphism of the population should be known well. In this study, we isolated mitochondrial DNA from epithelial cells of oral cavity of healthy individuals and we amplified a constant and an hypervariable segment of the mitochondrial DNA, with the PCR technique. We applied two different restriction enzymes to each region and run the DNA fragments in 3.5% agarose gel. We have not found different restriction sites in the constant regions of the 38 individuals in our study. On the other hand, loss of the resriction site for Hint I enzyme was detected in the hypervariable region in four subjects. Two first degree relatives of one subject and one first degree maternal relative of the second subject demonstrated the same feature. Maternal relatives of the other two subjects were not available at time of this study. This study is the first of many studies which should be carried out, before studying mitochondrial genetic diseases in this population. The results maybe insufficient in defining the polymorphim of the studied mitochondrial DNA region in our population, but the observed variations in the two sites display an expected pattern.VI This and smilar studies should be continued with using more markers, until getting statistically satisfactory and confident results.