Scientists have succeeded in breeding mice with a disease similar to human Down syndrome. Reported by TASS.
Down syndrome is caused by genetic defects and is incurable: patients have three copies of chromosome 21 instead of two in their DNA. Therefore, the genes responsible for the development and functioning of the brain cannot function properly. As a result, from childhood, a person lags far behind his peers in development, including in school disciplines. At the same time, scientists do not have an understanding of how this syndrome arises and develops. Its analogs were attempted to be induced in mice, but the model was flawed due to too many differences in the structure of human and mouse genomes. Specifically, genes on human chromosome 21 are shared between mouse chromosomes 10, 16 and 17 and a number of other chromosomes.
Now Diana Bianca and her colleagues have succeeded in inducing a disease in mice that is very similar to human Down syndrome. The biologists measured the activity of the genes in the brain cells of Ts65Dn mice and identified parts of their triplet chromosomes that may or may not overlap in structure with human chromosome 21. This approach allowed the biologists to identify 45 genes located on chromosome 17 of mice that simultaneously affect the functioning of the mice’s brain, but are not associated with the development of Down syndrome. With this idea in mind, the researchers developed a CRISPR/Cas9-based gene therapy that makes extra copies of these DNA regions in the germ cells of Ts65Dn mice.
This led to the emergence of a new species of rodent called Ts66Yah. Their representatives had a wide range of physiological abnormalities and cognitive symptoms, but at the same time did not display peculiar behaviors characteristic of Ts65Dn rodents and not characteristic of carriers of Down syndrome.
The authors hope that research using this model will help sick people or hypothetically save them from Down syndrome.
Formerly a substance for the treatment of obesity passed mouse tests.