CRISPR: Patients with edited genes closer to recovery


Sickle cell anemia and thalassemia are genetic diseases that result in the production of anomalous hemoglobin (protein that carries oxygen) and deformed red blood cells. There is no cure for these ailments, but ten patients who have had their genes edited are on their way to get rid of them, thanks to the Clustered Regularly Interspaced Short Palindromic Repeats technique or CRISPR.

“It is possible to edit human cells and safely infuse them in patients; this treatment has totally changed their lives,” said haematologist Haydar Frangoul of the Sarah Cannon Research Institute. He is the doctor accompanying the study’s first volunteer, the housewife and mother of three children Victoria Gray.

Gene editing has been used primarily in agriculture and was, on an ethically questionable occasion, responsible for creating genetically “improved” babies.

The path taken by scientists at CRISPR Therapeutics and Vertex Pharmaceuticals, both in the US, was to use the technique to edit a gene from stem cells taken from patients’ bone marrow.

The work consisted of activating the generation of fetal hemoglobin, which is still produced in the womb and which results in healthy red blood cells. When the baby is born, the gene turns off and, in patients with thalassemia and sickle cell anemia, the result is the production of anomalous hemoglobin, causing red blood cell deformation and death, shortage of healthy red blood cells, obstruction of blood flow, anemia, tiredness, pain and weakness.

Recreate from scratch

To receive the stem cells edited by CRISPR, patients first had to go through a painful stage: numerous rounds of chemotherapy to destroy most of their bone marrow (the side effects of the experimental treatment were only recorded at this stage).

After all the stem cells that produced the anomalous hemoglobin were destroyed, those edited were infused into the patients to reproduce and manufacture fetal hemoglobin.


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