Analysis of Mutational Burden of Mitochondrial Genome in Cells of Different Human Organs and Tissues

Background: Cells of different human organs and tissues contain different numbers of mitochondria. In these organelles, there are different copies of the mitochondrial genome, which is characteristic of a certain organ or tissue.

Objective: The aim of the investigation was to analyze the results of scientific works dedicated to the analysis of heteroplasmy levels of mitochondrial genome mutations in a number of organs and tissues.

Methods: Based on literature data, the level of heteroplasmy of mitochondrial genome mutations was analyzed in organs such as the liver, lungs, muscles, small intestine, large intestine, spleen, kidney, brain, heart, and hair. In addition, this parameter was studied in such tissues as leukocytes, buccal epithelium, and epithelial cells from urine.

Results: Significant differences in the mutational burden of the mitochondrial genome were found in various samples of organs and tissues. The highest heteroplasmy level for mtDNA mutations was in muscles; it was lower in buccal epithelium; and in human blood cells, the heteroplasmy level of mitochondrial mutations turned out to be significantly lower compared to other tissues. During the comparison of samples of patients with different diseases and healthy people, significant differences were found in the heteroplasmy level between some organs and tissues.

Conclusion: The heteroplasmy level of mitochondrial genome mutations can significantly differ in the organs and tissues of individuals. In addition, in a number of literature sources, it is noted that there is a dependence on the mutational burden of the mitochondrial genome from the type of disease, sex, and age of a person.