Genome editing, also known as gene editing, is the manipulation of the genetic material of a living organism by deleting, replacing, or inserting a DNA sequence, typically with the aim of improving a crop or farmed animal. It has more recently been used in humans. CRISPR-Cas9 is the most recent revolutionary technology that's making gene editing possible, with incredible results.
Plants, animals, and microorganisms like bacteria that have been genetically engineered are termed genetically modified organisms (GMOs). If the genetic material introduced to the host is from an organism that normally would not be able to breed with the host species, the new organism is called transgenic.
There are two ways that gene editing can be carried out. Genes and chromosomes mutate in one of two ways. One way is somatic mutation, which occurs in a single body cell and cannot be inherited (only tissues derived from the mutated cell are affected). The second way is germline mutations, which occur in gametes (reproductive cells) and can be passed to offspring (every cell in the entire organism will be affected). Genetic engineers choose the gene they want to insert into the target organism. Next, they isolate the gene and purify the DNA. The purified DNA is either cut into segments to remove traits or amplified (reproduced) as it is. This DNA is then inserted into a bacterium along with other genetic material, such as promoters and terminators, to initiate and stop the genes' reproduction. Researchers also insert genetic markers to help determine which cells have been successfully transformed. The bacterium containing the new DNA is then inserted into the target, or host, and then reproduced. Techniques to modify DNA in the genome have existed for several decades, but the conversation about the science and ethics of genome editing has grown louder due to faster, cheaper, and more efficient technologies.
Selective breeding, or artificial selection (dog breeding, animal husbandry, etc.), has been used by humans for thousands of years. More recently, mutation breeding uses exposure to radiation or chemicals to produce a high frequency of random mutations for selective breeding purposes.
Gene editing technology can be used to create “gene drives” that ensure a genetic modification will be inherited by all the offspring, spreading throughout an animal population over several generations. There are many advantages to this “godlike” technology.
For example, exotic pet breeding and faster racehorses are now possible. This technology also enables designer babies whose genetic makeup has been selected in order to eradicate particular defects, or to ensure that a particular gene is present. Just like an Amazon shopping cart, theoretically one could preselect hair color, eye color, height, half human/half horse—anything is possible.
One of the most fascinating use cases of gene editing is its capabilities in medicine. In this industry, genetic engineering is used for mass production of insulin, mass production of human growth hormones, mass production of a specific protein or enzyme, treating infertility, production of antibodies, increasing the success of organ transplantation, and the production of food supplements and foods like cheese. And that's just the beginning!
There are many ethical, social, ecological, and economic concerns over gene editing and its use cases. As with many new technologies, there is concern that genome editing will only be accessible to the wealthy and will increase existing disparities in access to healthcare and other interventions. Some worry that taken to its extreme, gene editing could create classes of individuals defined by the quality of their engineered genome. That it could lead to a resurgence of the eugenics movement. Furthermore, folks in control of the technology could control the food supply with the use of intellectual property rights.
Safety concerns include the possibility of off-target effects (edits in the wrong place) and mosaicism (when some cells carry the edit but others do not), or even unexpected or harmful genetic changes and mutations. For example, an attempt to control or eradicate invasive species or pests such as the malaria-causing mosquito could lead to an accidental eradication of bees. Without bees, we have no pollination, which means no food. And lack of food would lead to the extinction of humanity.
Gene editing technology could theoretically be used to enhance, modify, or alter a human being's appearance, adaptability, intelligence, character, or behavior. It's not hard to imagine a dictator creating a rogue army that has been genetically modified not to have feelings. The 20th century was dominated by advances in physics that led to the development of the most destructive weapons humanity has ever created. Advances in biotechnology over the last few decades promise to make the same true for the 21st century. The biological revolution is set to produce tools that could be turned into weapons of war. Gene editing is the latest in a series of biological advances that will fundamentally change how humans live and die.