Health. Down syndrome: Researchers successfully remove the extra chromosome
Japanese researchers have used a novel technique to treat Down syndrome (trisomy 21) in vitro. Using "molecular scissors," they were able to remove the extra chromosome from trisomy 21 cell lines.
Trisomy 21, or Down syndrome, is a chromosomal abnormality caused by the presence of an extra chromosome 21, 3 instead of 2. According to the United Nations, the prevalence of Down syndrome is estimated at between 1 in 1,000 and 1 in 1,100 live births worldwide.
Researchers at Mie University in Japan have used new genome editing techniques to treat Down syndrome directly in cells in in vitro tests. These innovative techniques are used to modify the DNA sequences that make up the genome.
Specifically, the researchers were able to target and remove chromosome 21 in Down syndrome cell lines created from skin cells, using the CRISPR/Cas9 system.
Awarded a Nobel Prize in 2020, it is "a new, simple, fast, and efficient system for cutting DNA at a specific location in the genome, in any cell. It consists of a 'guide RNA', which targets a particular DNA sequence, associated with the Cas9 enzyme, which, like molecular scissors, cuts the DNA," explains AFM-Téléthon.
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These results, published in February 2025 in the journal Pnas Nexus , were observed in induced pluripotent stem cells ( iPSCs ) as well as in fibroblasts. iPSCs , widely used to model many human pathologies, are specialized body cells, genetically reprogrammed in the laboratory.
This causes them to lose their speciality and they then function like embryonic stem cells. As for fibroblasts, they are poorly differentiated cells, precursors of connective tissue. Very present in the skin, these support cells serve to maintain and maintain the body's tissues.
After removing the extra chromosome from the cells, the Japanese team observed a return to "normal" gene expression and cellular activity. For now, the technique cannot be applied to humans.
However, scientists believe that a similar technique could be used in people with Down syndrome, on neurons and glial cells, which maintain neurons. However, since Down syndrome is not a curable disease, this scientific advance also raises ethical questions.
Source: Inserm, AFM-Téléthon, Pnas Nexus
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