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The development of dementia in non-inherited cases may be influenced by errors in our DNA that occur when cells divide and replicate, according to a newspaper article. Nature Communications.
Dementia is a general term used to describe several neurodegenerative disorders. It is thought that only 5% of cases are due to rare hereditary mutations of the genetic code, transmitted by one or both parents. The causes of the vast majority of cases, in which there is no family history, remain a mystery.
Scientists know that common types of dementia, such as Alzheimer's disease and Parkinson's disease, are characterized by an accumulation of toxic proteins in the brain, which destroy brain cells and damage brain regions, causing brain damage. symptoms such as personality changes, memory loss and reduced motor skills.
At present, a team led by researchers at the University of Cambridge has suggested that clusters of brain cells containing spontaneous genetic errors could lead to the production of these toxic proteins, which could possibly spread through the brain .
"As the world's population ages, we are seeing more and more people affected by diseases such as Alzheimer's, but we still do not sufficiently understand the majority of these cases," said Patrick Chinnery, of the Mitochondrial Biology Unit of the Medical Research Council. Department of Clinical Neuroscience Cambridge, said in a statement.
"Why do some people contract these diseases while others do not? We know that genetics play a role, but why do not people with a family history develop the disease? ", Did he declare.
For their research, scientists examined 173 tissue samples from 54 individuals stored in the UK Brain Banks network. Fourteen of these people were in good health, 20 with Alzheimer's disease and another 20 with a common type of dementia called Lewy's disease.
The team then used an advanced technique to sequence 102 genes in tissue samples over 5,000 times. These genes include those that are known to cause or predispose people to common neurodegenerative diseases. This approach revealed "somatic mutations" – errors occurring spontaneously in DNA rather than hereditary viruses – in 27 samples of brain tissue diseased brains.
These results suggest that mutations occurred during the developmental stage, when the embryo was developing in the uterus.
"We found that half of the brains we studied contained somatic mutations that may occur during brain development," Chinnery said. Newsweek. "Using a [mathematical] model, we made predictions about the frequency of mutations in each of us. Our predictions suggest that we all have brain cell fragments containing mutations [alterations in the genetic code] and that this will sometimes affect the genetic code known to cause diseases such as Alzheimer's disease. "
"These errors occur in our DNA when cells divide and could explain why so many people develop diseases such as dementia while the individual has no family history," Chinnery said. . "These mutations probably form when our brain develops before birth. In other words, they've been sitting around waiting to cause problems when we're older. "
"Our discovery could also explain why there are no two cases of identical Alzheimer's or Parkinson's," he said. "Errors in the DNA of different brain cell models may manifest as slightly different symptoms."
Currently, it is too early to say whether the results of the study could help in the diagnosis and treatment of dementia. The researchers believe, however, that the results could validate the approach of pharmaceutical companies trying to develop new treatments for the rarer types of genetically inherited neurodegenerative diseases.
"The question is: what will be the relevance of these treatments for the common or garden variety without family history?" Said Chinnery. "Our data suggest that the same genetic mechanisms could be responsible in non-inherited forms of these diseases, so that these patients can benefit from treatments developed for rare genetic forms."
According to Chinnery, further research is needed to determine whether mutations are more common in dementia patients and thus confirm whether they actually contribute to its development.
David Reynolds, Scientific Director of Alzheimer's Research UK, who did not participate in the latest research, praised the quality of the study but cautioned that the results should be considered with caution at the moment.
"We know that the development of dementia is influenced by a complex combination of factors related to age, genetics and lifestyle," he said. Newsweek. "Our genetic makeup can have a huge impact on our health and errors in this DNA code can occur during embryonic development as well as throughout our lives."
"This well-conducted research using advanced DNA sequencing technology has allowed scientists to look more than ever at the genetic differences between brain cells," he said. "Although researchers have discovered DNA errors in genes associated with neurodegenerative diseases, the study was not important enough to reveal whether or how these errors could directly contribute to the development of a disease like Alzheimer's."
He explained that in recent decades, genetic clues have been crucial in discovering new areas of biology to explore in the search for treatments for diseases such as Alzheimer's disease.
"This study provides a valuable platform for further research to continue to understand the complex role our genes play in the development of diseases that cause dementia," said Reynolds.
This article has been updated to include additional comments by Patrick Chinnery.
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