By Ian Murray
Those who follow STEM news sources have doubtlessly heard the phrase “CRISPR Cas-9,” if not the details of how it works, but even those who insulate themselves from learning about technological advancements will likely find themselves encountering the term before too long. But what is Crispr? How does it work? What are its limitations? To answer this question, we need to go back to 1987, to a laboratory in Osaka.
In this lab, biologist Yoshizumi Ishino is working with E. Coli genes, where he discovers a strange part of the genome, where lines of genetic code repeated themselves at regular intervals, interspersed by mysterious interruptions. Further research throughout the 90s and 2000s shows that many other bacteria genomes contain similar sequences. Eventually, these sequences are given the name CRISPR, short for Clustered Regularly Interspersed Short Palindromic Repeats.
It is not until 2005 that the function of the CRISPR codes are discovered. As it turned out, the mysterious lines of code between the repeating sequences were actually the genomes of viruses which had been killed by the bacteria, which were cut out by a protein called Cas-9. This protein has a rough clamshell shape, and acts like a pair of scissors, guided to a particular spot on the target genome via gRNA. The function of cutting out and assimilating these genomes is to act as genetic “mugshots,” allowing the bacteria to identify infectious types of virus.
It wasn’t long after this discovery before the potential of CRISPR became apparent to biologists. If this protein can selectively cut out particular pieces of other cell’s genomes with near-unerring precision, what’s to stop a genetic engineer from using it to selectively delete any piece of a chosen organism’s genome and replacing it with a different gene? The answer: nothing. If we think of an organism’s genetic code as analogous to a computer code, than CRISPR Cas-9 can be thought of as a powerful and versatile editing software.
In 2012, three independent teams of researchers, led by Jennifer Doudna, Feng Zhang (whose name coincidentally means “vanguard” in Mandarin), and George Church, published papers explaining how to modify human cells with CRISPR. In the 7 subsequent years, thousands of papers have been published exploring the possibilities of CRISPR gene-editing. A few of the more world-changing possibilities include: preventing Cystic Fibrosis and Sickle Cell Disease in embryos, lowering an embryo’s risk of Alzheimer’s, making mosquitoes resistant to infection with malaria, making crops yield more edible material, and allowing parents to select eye-color- hair-color- and height in their future children.
What are the legal and philosophical implications of this technology? Stan Lee famously wrote “With great power comes great responsibility” and nowhere does that sentiment ring more true than in the world of human genetic engineering. This is a topic I will be considering in articles to come, as the topic bears in-depth discussion.