A study showed that the use of various CRISPR genetic editing tools can be effective in eliminating the extra copy of chromosome 21, responsible for Down syndrome. Research, conducted by a group of Japanese scientists, suggests that this approach could be applied to neurons and other nerve cells with the aim of developing a possible cure for this condition.
Down syndrome originates from the presence of a third or partial copy of chromosome 21. This chromosomal anomaly affects 1 in 700 living beings and can be diagnosed with relative ease in the early stages of development. People with this condition have a wide range of distinctive morphological and anatomical characteristics. In some cases, congenital defects may arise that cause heart, digestive, auditory and eye problems, as well as intellectual disability, obesity, motor and neurological alterations. The severity of these problems varies and directly influence life expectancy. To date, there is no definitive cure for this condition.
Ryotaro Hashizume, researcher at the Department of Pathology and Matrix Biology of the Faculty of Medicine of the University of Mie, has developed with its colleagues a genetic editing technique that allows identifying and eliminating the additional chromosome. His work recalls that each individual inherits a copy of each chromosome from his mother and another of his father. In cases of Down syndrome, one of the parents transmits two copies of chromosome 21, which gives rise to the trisomy. However, These copies are not identicalsince they can contain genetic variants that influence gene activity.
This particularity has been key in the new study, which managed to identify specific sequences in one of the duplicate chromosomes to intervene through more than 50 tools of the CRISPR-CAS System. This genetic editing technology uses an RNA molecule specially designed to guide an enzyme towards a certain DNA sequence. Once there, the enzyme cuts the DNA strands at that point, which allows to eliminate a small section. As a result, the modified cell retains only two copies of chromosome 21, one in each parent, thus correcting the trisomy.
“We develop a sequence extraction method Objective of Specific Harels CAS9, known as AS, which efficiently eliminates the target chromosome, unlike less specific previous strategies,” explain the authors in a Published article In the magazine PNAS NEXUS. “The temporal elimination of DNA damage response genes increases the loss of chromosomes, while The chromosomal rescue restores genetic firms and improves phenotypes. So it is effective, even in differentiated cells, and could revolutionize the treatment of trisomy 21 ”,
The experiment was carried out in induced pluripotent stem cells and fibroblasts cultivated in the laboratory. Researchers recognize that their methodology is not yet ready to apply in living organisms, since the current technique can also affect the chromosomes that are preserved. “In future investigations, we will focus on better understanding the mechanism of loss of chromosomes treated with CAS9, as well as evaluating the possible long -term consequences that these modifications persist in the genome,” they conclude.
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