mtDNA for early prediction of morbidity and mortality risk

Researchers from Johns Hopkins University, working under the guidance of Dr. Dan Arking, have obtained results indicating that the amount of mitochondrial DNA (mtDNA) in a blood sample reflects the state of human health. This indicator can be a useful prognostic factor for assessing the overall risk of deterioration of health and death from any cause 10-15 years before the onset of symptoms.

Mitochondria are organelles that produce most of the energy necessary for the vital activity of the cell and are therefore often called its "energy centers". Unlike other intracellular structures, mitochondria have their own DNA. It is represented by 2-10 small ring chromosomes encoding 37 genes responsible for the functioning of mitochondria. Depending on its energy needs, a cell can contain from 10 to several thousand mitochondria.

The results of earlier studies of the authors demonstrated the existence of a relationship between genetic differences in mtDNA and "senility", as well as muscle weakness of older people. From a medical point of view, "decrepitude" is a detailed set of symptoms of aging, including weakness, decreased energy and activity levels, as well as a decrease in body weight. To study this relationship in more detail, the researchers analyzed the amount of mtDNA in human blood samples collected in two studies that began in the late 1980s and tracked the health status of participants for 10-20 years. A total of 16,401 people took part in both studies, of which almost 45% were men.

After determining the ratio of the amount of mtDNA to the amount of nuclear DNA in each of the samples, the researchers compared the data obtained with data on the senility and health status of the participants collected during both studies.

On average, the amount of mtDNA in the blood of participants whose condition met the 9 criteria of senility was 9% less than the amount of mtDNA in the blood of participants with good health. When analyzing the data taking into account race, it was found that participants with white skin color, who were in the 20% with the lowest mtDNA content in the blood, were 31% more likely to be characterized as senile.

The researchers also analyzed the age of death of participants in both studies. It turned out that for participants in the 20% with the highest mtDNA content in the blood, the probability of death during the study period was 47% (almost one and a half times) higher than for 20% of participants with the lowest mtDNA content.

Percentage of participants who survived during the observation period (of European origin)
programs for studying the risk of cardiovascular diseases (Cardiovascular Health Study, CHS).
Q1 – 20% of participants with the highest mtDNA content in the blood, Q5 – 20% with the lowest mtDNA content.
Poster from the report of The Arking Lab at the congress of the American Society of Human Genetics on October 21, 2014

It was also found that the mtDNA content in the blood of women is on average 21% higher than that of men. The authors suggest that this may contribute to the fact that the average life expectancy of women is 2-4 years higher than the average life expectancy of men.

According to Dr. Arking, the researchers want to conduct a new work in which they will analyze the change in the content of mtDNA in the blood of people for several years. According to preliminary conclusions made on the basis of the processed data, every 10 years the concentration of mtDNA in human blood decreases by an average of 2.5%.

The authors believe that the data they have obtained deepen the scientific understanding of aging and can form the basis of a test to identify people at risk of premature death, whose physical condition can be improved with the help of medications or lifestyle changes.

Article by Foram N. Ashar et al. The Association of mitochondrial DNA levels with frailty and all-cause mortality is published in the Journal of Molecular Medicine.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on Johns Hopkins University materials:
Amount of Mitochondrial DNA Predicts Frailty and Mortality.

22.12.2014