Dominant dementia
Geneticists from Russia have discovered a mutation that causes mental retardation
Large-scale genetic testing of Russians helped scientists from the Bochkov Medical and Genetic Research Center discover a previously unknown mutation that causes mental retardation. The press service of the organization tells about the opening.
"Now the causes of the so-called dominant mental retardation caused by mutations that the child's parents do not have are increasingly being discovered. They occur at different stages of embryo formation and development, and these are, most often, random events in genes that cannot be influenced," notes Olga Levchenko, a researcher at the MGNC genome editing Laboratory.
In addition to the famous Down syndrome, scientists have discovered dozens of other forms of severe mental disorders associated with the appearance of small mutations, extra copies of genes and other forms of "typos" in DNA. The study of these parts of the genome is of great interest to both physicians and evolutionists who study how humanity appeared and why we are so different from other primates.
Many of these mutations are very rare among the population, which is why their discovery is an extremely long, time-consuming and difficult process that requires a lot of effort. According to current WHO estimates, approximately 30-50% of cases of mental retardation still remain without a clear explanation of what exactly they were caused by.
The situation, as Levchenko notes, is complicated by the fact that some mutations that cause such problems are absent from the child's parents. This means that they appeared after the conception of the child, during its intrauterine development. The search for such "typos" in DNA is possible only if you decipher and study not only the patient's genome, but also his mom and dad.
According to the ISTC press service, every year 11 thousand patients undergo high-tech genetic testing at the direction of a doctor, free of charge. And those who meet the selection criteria further participate in scientific programs, where they are already undergoing a full-exome study.
"This year, 40 places have been allocated for patients with mental retardation to participate in the scientific program. Since the beginning of the year, we have tested 14 patients and their parents, some more patients have been recruited, there are still eight places left," the geneticist continues.
These studies, she said, brought an unexpected discovery – in one of the patients, scientists found a small mutation in the AFF3 gene, which does not occur in his parents. This section of DNA used to be associated with leukemia and scientists did not suspect that it could be somehow involved in the development of mental retardation.
Having discovered this DNA damage, Russian scientists contacted geneticists from Switzerland, who helped them confirm that a similar connection really exists and find other patients with a similar mutation in AFF3. Interestingly, all its carriers acquired this gene damage on their own, and did not inherit it from their parents.
This gene damage, scientists suggest, leads to disruptions in the processing of certain protein molecules and disrupts brain development. The discovery of this mutation allowed Russian and Swiss researchers to discover a new syndrome called KINSHIP. In the near future, its full description will be published in one of the peer-reviewed scientific journals.
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