New research has identified mutations in the DNA code that can affect energy metabolism and which, in turn, may be related to major depressive disorder.
The World Health Organization (WHO) describes depression as “the leading cause of disability worldwide,” a global problem that affects 300 million people worldwide and is affected by numerous factors, from genetics to environmental factors, food, substance use, brain physiology or immune system.
There is a theory that discusses that disturbances in the brain’s energy metabolism could cause major depressive disorder. In a recent study, the researchers removed the Sirt1 gene in neurons of male mice. The result was a drastic reduction in the number of mitochondria in these cells, accompanied by symptoms similar to depression.
Mitochondria, the so-called cell power plants, are specialized compartments that convert the nutrients we ingest into the chemical energy our cells require to function. Each cell has many mitochondria to ensure an energy supply without problems. However, by reducing their number or interrupting the intricate metabolic pathways, cells can die due to lack of energy.
In an article recently published in the journal Nucleic Acid Research, scientists used bioinformatics tools to identify large mutations in the genetic code of mitochondria, finding a significant molecular signature of these in a subset of brain samples with depression.
Scientists know that deletions, a type of DNA mutation in which a large part of the genetic code is missing, cause a series of mitochondrial diseases. The study’s lead author, Brooke E. Hjelm, an assistant professor of clinical translational genomics at the University of Southern California in Los Angeles, said researchers had already identified about 800 deletions – structural chromosomal abnormalities – in the mitochondrial genome.
The research employed an analysis tool used for the research community called MapSplice, developing a process to detect and quantify mitochondrial deletions. In the 93 human samples, which came from 41 deceased individuals, included in the study, he discovered about 4,500 deletions.
“There are deletions that had previously only been seen in one or a few people with a diagnosis of mitochondrial disease, suggesting that they are rare, when in reality it is likely that these eliminations occur in all of us, they are simply not present at a rate high enough to cause illness,” he said.