“I am proof that miracles can happen! » The testimony of Victoria Gray, 37 years old, four children, “sickle cell survivor”moved the participants of the 3e International Summit on Genome Editing, held in London from March 6-8. The young American recounted how the Crispr-Cas9 genome-editing technique changed her life, punctuated since childhood by hospital stays and severe pain induced by the poor circulation of her shaped red blood cells. sickle. Sickle cell disease, also called sickle cell anemia, sometimes prevented her from walking and feeding herself, and shattered her dream of becoming a nurse.
His relatives feared for his life, until his hematologist told him about Crispr-Cas9, and a clinical trial to fight against the disease. At the TriStar Centennial Hospital in Nashville (Tennessee), Doctor Haydar Frangoul explains the procedure to her: she will first have to undergo chemotherapy intended to put her immune system to sleep, so that her body accepts hematopoietic cells (which give rise blood cells by dividing) given by his brother. These cells will have previously been genetically modified by Crispr-Cas9 in order to produce fetal hemoglobin again to replace the failing hemoglobin responsible for the deformation of its red blood cells.
The treatment, started in June 2019, is not a path cobblestone roses: hair loss, canker sores that prevent him from eating, three-month hospital stay away from his family… “It took seven to eight months before I noticed an improvement”, she explains, as the Covid-19 adds to her anxiety. But today she can « play football with [ses] children, who are no longer afraid of losing their mother to sickle cell disease”.
This therapeutic success on the most widespread monogenic disease in the world – 300,000 to 400,000 carrier children are born each year – was described in early 2021 in the New England Journal of Medicine by the team of Haydar Frangou, who worked with the American-Swiss start-up Crispr Therapeutics and the American company Vertex Pharmaceuticals. These last hope to obtain marketing authorization for this treatment from the American and European health authorities in 2023 or 2024. It would then be the first authorized therapeutic process using Crispr-Cas9.
“It’s an extraordinary breakthrough when you consider that it’s a technology that is barely ten years old”, said Jennifer Doudna, professor at the University of California at Berkeley and founder of the Institute for Innovative Genomics. She shares with Frenchwoman Emmanuelle Charpentier, herself the founder of Crispr Therapeutics, the 2020 Nobel Prize in Physiology and Medicine for the joint discovery of the Crispr-Cas9 system. Inspired an immune mechanism present in bacteria to fight against viruses, this complex molecule makes it possible to target a portion of the genome to cut it out in order to alter genes, and possibly rewrite it. Its simplicity and versatility have given these molecular scissors the nickname of “Swiss army knife of genome editing”.
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