For the very first time in the world, Chinese Scientists have claimed to edit DNA in human embryo. Junjiu Huang and his colleagues experimented editing some human embryos that can alter the gene called HBB which is responsible for causing a fatal blood disorder known as beta-thalassemia. This experiment was performed at the Sun Yat-sen University in Guangzhou, China using some new technology where they injected the CRISPR/Cas9 complex into human embryos.
The general idea was to replace a bad piece of human embryo that harbored a mutation that cause a certain blood disorder with a good piece to eliminate that particular disorder. The same technology could be used in other potential diseases based on single gene mutations, including Huntington’s disease, cystic fibrosis, sickle cell anemia, and Tay-Sachs disease. However the embryos are obtained from local fertility clinics and could not result in live births because they have been fertilized by two sperm, which prevents the embryos from developing properly.
The researchers performed the procedure on 86 embryos, and waited four days to allow the gene editing to take place. Seventy-one of the embryos survived, and the researchers genetically tested 54 of them. Only 28 embryos were spliced successfully, meaning the faulty gene was removed, and just a few of those incorporated the healthy gene in its place.
This technique involves an enzyme complex known as CRISPR/Cas9, found in many bacteria to match the genetic sequence the researcher wants to modify. It works in concert with Cas9, an enzyme that cuts DNA like a pair of molecular scissors. First, the CRISPR/Cas9 complex searches through the cell’s DNA until it finds and binds to a sequence that matches the CRISPR. Then, the Cas9 cuts the DNA. Lastly, the cell repairs the cut, in this case by inserting a piece of DNA supplied by the experimenter.
A method called CRISPR used for gene editing where it exploits a system that bacteria uses to protect itself from the viruses and allows the researchers to cut out the selected genes and insert new ones. However, the procedure also caused bothersome mutations in other parts of the genome — and at a much higher rate than in mouse embryos or adult human cells undergoing the same procedure. These mutations could have adverse effects on cells, which is one of the big concerns about gene editing.
Genome editing in human embryos using current technologies could have unpredictable effects on future generations that makes it dangerous and ethically unacceptable. Scientists are not fully clear on the role of DNA and its genes but future research on the technique may improve the accuracy and efficiency.