The discovery of CRISPR has made for an interesting few years in the realm of genetic research. It meant we can make permanent edits to a genome with the aid of the CIRSPR/Cas9 system, but there has been a great deal of concern over how to use this powerful technology. Researchers in the US have limited CRISPR experiments on the human genome, but for the first time, a US team has successfully edited a human embryo with CRISPR(Opens in a new window). In doing so, the scientists at Oregon Health and Science University also showed CRISPR has the potential to eliminate genetic diseases.
What makes CRISPR so exciting is its ability to make changes to DNA inside living cells. It is theoretically possible to alter an organism's entire genome if changes are made in the embryonic stage when it is composed of only a handful of cells. Several published studies from China have involved editing human embryos, but the teams involved identified several potential issues that cast doubt on CRISPR's ability to modify a person's entire genome. The new US study, led by Shoukhrat Mitalipov, not only modified more embryos than past experiments, it showed much more promising results.
When editing an embryo, you have a chance to change the genes in all the resulting organism's cells. That means the changes you introduce would propagate through successive generations. Should that modification eliminate a defective gene that causes disease, you prevent that disease from appearing in the organism's descendants. It's clear why this is such an attractive idea, but the first few attempts with human embryos showed incomplete transfer of modified genes to all cells. This results in a condition called "mosaicism," where some cells have a different genetic composition.
How CRISPR works.
Mitalipov's team was able to produce complete uptake of the modified genes by getting to the embryo earlier. CRISPR editing was performed shortly after the egg was fertilized with sperm carrying a genetic abnormality. The team successfully eliminated that defect in dozens of embryos. None of the embryos were allowed to develop beyond a small cluster of cells, but this potentially opens the door to clinical trials to eliminate genetic disease with germline engineering.
Some will no doubt be worried this technology will inevitably lead to "designer babies" with enhancements that go beyond the elimination of diseases. However, US law still blocks any effort to turn edited IVF embryos into babies. Clinical research will likely continue in other countries without such laws.
Now read: What is gene therapy?
