The Chinese have conducted a unique experiment on DNA correction
The Medical University of Guangzhou has conducted an unusual experiment. The scientists corrected genetic mutations in the cells of viable human embryos using CRISPR genome correction method. Previously, no one research group carried out such experiment. The main difference of this experiment was the use of normal embryos. Previously, CRISPR was tested only on genetically defective embryos that cannot develop into a fetus. It turned out that the method works much better with normal embryos.
Initially, the editing method successfully restored less than one cell out of ten when defective embryos were used. That is, the efficiency factor was too low. The efficiency factor was higher in normal embryos obtained from ovules left after IVF cycles.
For the latter experiment, the scientists developed ovules donated by patients of IVF clinics. Then the cells were fertilized by adding sperm of men with hereditary diseases. After this procedure the CRISPR correction method was used (performed before the cell starts its division). The first sperm donor was a man with G1376T mutation in the gene of G6PD enzyme. This mutation often causes favism. This is a disease where the use of certain products can cause the destruction of red blood cells.
The method has corrected G1376T mutation in two embryos. However, all cells were corrected in the first embryo, but in the second one some problem cells remained. The second sperm donor was a man with beta41-42 mutation that causes beta-thalassemia (all four embryos had this mutation). In the first embryo CRISPR method has caused a new mutation. In the second embryo the mutation was successfully corrected only in some cells, and in the other embryos the method did not work at all. Despite this, the efficacy of the method was improved significantly.