Scientists have described the molecular basis of Down syndrome

Oleg Lischuk, N+1

American researchers have found out how Down syndrome affects the development and function of the brain at the molecular level. It turned out that the main disorders are associated with a white substance consisting of nerve fibers. The results of the work are published in the journal Neuron (Olmos-Serrano et al., Down Syndrome Developmental Brain Transcriptome Reveals Defective Oligodendrocyte Differentiation and Myelination).

Down syndrome is a congenital disease associated with the presence of an additional 21st chromosome. It causes multiple developmental disorders, mainly of the nervous and cardiovascular systems. His symptoms have been described for a long time, but it was not known exactly what changes in the structure and work of the brain lead to them.

An interuniversity research team led by employees of Boston and Yale Universities analyzed transcriptomes of various brain regions of transgenic mice with an analogue of human Down syndrome and healthy animals (a transcriptome is a set of informational RNAs that provide protein synthesis on a DNA matrix; it serves as an integral indicator of the function of cells and tissues consisting of them). The study used mice of both sexes from mid-fetal development to adulthood. The correspondence of the animal model to the human disease was confirmed by studying changes in the brain tissues of deceased people with and without Down syndrome.

It turned out that in Down syndrome, the expression of many genes is disrupted, and these disorders have a clear spatiotemporal specificity, are associated with specific biological processes and are observed throughout the genome. In particular, significant changes in the expression of genes associated with the maturation and viability of oligodendrocytes – auxiliary cells of the central nervous system, which serve as support and insulation for nerve fibers and synthesize their myelin sheaths.

As a result, the myelination of nerve fibers decreases, which, in turn, leads to a violation of the development of the white matter of the forebrain and a slowdown in the passage of nerve impulses in it. As a result, there is a set of intellectual and neurological disorders characteristic of Down syndrome.

A cross-section of nerve fibers of the white matter of the brain is normal (left)
and with Down syndrome. Deformed myelin sheaths are visible.
A drawing from an article in the journal Neuron.

"The discovery of genetic changes that lead to disruption of connections between brain regions provides a completely new target for potential therapy of Down syndrome. The results obtained will allow us to develop new strategies for improving brain functions and improving the quality of life," said Tarik Haydar, head of the work, in a press release "Discovery of key abnormality affecting brain development in people with Down syndrome".

Portal "Eternal youth" http://vechnayamolodost.ru  03.03.2015