The Chinese government announced regulations requiring research approval for gene editing, Science Magazine reported. This statement follows the news that China had produced two genetically-altered babies. We’ve come a long way from blasting radiation at insects.
Scientist He Jiankui claimed in November 2018 that he had manipulated two human embryos to make them and their descendants resistant to HIV. The technology he used, called CRISPR, is still in its early stages and He has since suffered widespread criticism for tampering with unsafe methods that could cause permanent damage to the babies on whom he experimented. Gene editing may allow us to take evolution into our own hands, but how did we get here?
The Early Days of Human Genetic Manipulation
In the 1920s, Herman Muller experimented with gene editing by blasting fruit flies with chemicals or radiation that caused mutations. These chemicals, called mutagens, led to various physical abnormalities that Muller could study. “But bombarding genes with mutagens was very crude,” Dr. Scott Solomon, Associate Teaching Professor at Rice University, said. “Researchers couldn’t predict where in the genome a mutation would occur. And most of the mutations would be harmful, disrupting genes that perform essential functions, and often leading to death before the mutations could even be observed.”
In 1972, 50 years later, biochemist Paul Berg made headlines for successfully testing the concept of “recombinant DNA,” in which scientists remove DNA from one organism and combine it with the DNA of a different organism. Using base pairing, Berg “copied a short piece of DNA from a bacterial virus into a monkey virus,” Dr. Solomon said. The following year, geneticists Herbert Boyer and Stanley Cohen replicated his success. Boyer and Cohen found that frog genes could be permanently added to bacterial DNA and even be inherited by future generations of the bacteria. Increasingly complex organisms were edited for the remainder of the 20th century. The need to copy-paste genes remained until the invention of the CRISPR technology in 2012, which He used to produce the HIV-resistant embryos.
Fine-Tuning Human Genes with CRISPR
Biologists Jennifer Doudna and Emmanuelle Charpentier recently developed a two-part technology that lets scientists perform much more precise genetic engineering. “The first part is called Clustered Regularly Interspaced Short Palindromic Repeats, or CRISPR for short,” Dr. Solomon said. “CRISPR is a piece of RNA that searches for a particular sequence of DNA bases found in a virus’s genome.” The second part, an enzyme called Cas9, specifically cuts the DNA at exactly the point specified by CRISPR. This gives scientists the ability to find a specific virus and cut its genome before it can cause harm. Dr. Solomon explained that using Cas9 is similar to a laser-guided missile that bacteria can use to target and attack viruses.
“Most importantly, when Cas9 makes a cut in an organism’s genome, the organism will attempt to repair the cut,” Dr. Solomon said. “To do so, it will remove the DNA base at the location of the cut and replace it with a new DNA base that will seal the cut and repair the damage.” However, the new DNA base can be different from the original, so precise edits can be made to the DNA sequence of any organism.
The obvious benefits of gene editing include eradicating diseases like Sickle Cell Anemia and hemophilia. Unfortunately, unintended alterations to DNA also occur with CRISPR and Cas9. Ultimately, society will face ethical questions regarding the use of gene editing for purposes such as producing children tailor-made for specific hair and eye colors, physical and psychological traits, and so on. Chinese scientist, He Jiankui, has already undertaken a major step in using the risky technology to produce gene-edited babies who may be resistant to HIV. China’s subsequent regulations regarding the experiment will likely be the first of many regulations to come.
Dr. Scott Solomon contributed to this article. Dr. Solomon is an Associate Teaching Professor at Rice University, where he teaches ecology, evolutionary biology, and scientific communication. He received his Ph.D. in Ecology, Evolution, and Behavior from The University of Texas at Austin, where his research explored the evolutionary origins of biodiversity in the Amazon basin.