The Promise of Gene Editing

By Drs. David Niesel and Norbert Herzog

Genetic manipulation of animals and plants is actually not a new phenomenon. Humans have been selecting for desirable traits in foodstuffs for thousands of years through selective mating and breeding. This is proven technology but it can take decades to produce an animal with the desired traits. The advent of genetic engineering brought about the ability to add desirable genes quickly to foodstuffs. These are referred to as GMO or genetically modified organisms. For example, corn has been engineered to contain the insecticidal protein, Bt, a protein that protects plants by killing insects that ingest it. Another example are soybeans and other food plants that have been genetically modified to be resistant to the herbicide Roundup.

These genetic tools have had a huge impact. It is estimated that more than 75 percent of processed food products in the US contain GMO plant content. Think about how many foods you eat that contain corn, wheat and oils, which are the most prevalent genetically modified foods.

With a new gene editing technique called CRISPR (called Crisper), creating new GMOs by directly manipulating gene sequences has recently become a whole lot easier. Recently, a GMO salmon that is part Atlantic and Chinook salmon and contains a growth promoting gene that doubles the growth rate and the size of the fish was approved for human consumption by the FDA.

CRISPR has created a revolution in modifying the genomes of bacteria, plants and animals. CRISPR is found in bacteria and could be described as the immune system of microbes that protects them from invading viruses (yes, bacteria have viruses that attack them too!). It was first described in 1993 in a bacterium from a salt marsh. By 2014, CRISPR was being used for gene editing in a wide range of organisms from yeast to monkeys. This genetic technique can be used to remove or inactivate defective genes, correct mutations or even replace genes in an organism's genome. The development of CRISPR as a gene editing tool is a testament to science as a world-wide venture involving scientists in nine different countries. It is also another example that we never know where the next big innovation in science is coming from. Who could have predicted that a discovery involving bacteria from a Spanish salt marsh in 1993 would have been developed over 20 years to represent one of the most promising technologies of today?

And this technology is pushing scientific boundaries. In 2015, Chinese scientists reported the first successful manipulation of non-viable human embryos. This launched concerns about "designer babies" and resulted in the 2015 International Summit on Human Gene Editing. This summit explored the ethical concerns of this technology and its potential to make genetic changes that could be passed down to future generations.

We are in a new era in producing genetically altered plants and animals for agricultural use. This technology is also being explored to treat human disease. In the future, we are likely to see treatments for genetic diseases like cystic fibrosis, sickle cell anemia and even new ways of addressing human cancers. However, scientists will have to tread carefully when developing this capability as we create new advances in biology and medicine.

Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.