An Introduction to CRISPR
Highly precise genetic modifications are no longer stories from the realm of science fiction. A genome editing technique known as CRISPR is being touted as a revolutionary technology that promises to cure serious diseases, bring back extinct animal species (woolly mammoth anyone?), or even give rise to...designer babies!
These capabilities may sound remarkable, impossible, unethical, or some combination of all three, but all of them have played a role in generating a sense of mystery and apprehension about the technology.
This month, the Singularity University tech scouting team shines the light on CRISPR. What is it? How does it work? And what can it really do?
CRISPR is a type of genome editing technology. Genome editing (or gene editing) is a process in which DNA is inserted, deleted, or replaced in the genome of a subject, such as a mouse (or a human), using “molecular scissors.”
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. It dates back to the 1980s, but only within the last few years has a more simple version—the one we all know and talk about—been modified by scientists to edit genomes.
The technique is based on a process used by bacteria to protect themselves against infection from viruses. When the presence of viral DNA is detected, two short strands of RNA are produced, one of them being a direct copy of the viral DNA.
These RNA strands form a complex known as Cas-9 (which is why sometimes you’ll see CRISPR written as CRISPR-Cas 9), which finds and cuts out the viral DNA, thereby disabling the virus.
Scientists have taken this technique and essentially modified it to cut out mutated sections of DNA and replace them with healthy copies. Additionally, scientists found that this system could be engineered for the DNA in any cell of any animal, including humans.
How does CRISPR work?
Not the first kid on the block
CRISPR isn’t the only genome editing tool around. ZFN (Zinc Finger Proteins) and TALEN (Transcription Activator-like Effector Nucleases) are CRISPR’s older counterparts. While both of these are powerful tools, the new kid on the block has a number of advantages:
- Affordability: Using RNA formations instead of DNA binding domains cuts down the cost significantly, from around $5,000 to as little as $30 per mutation.
- Efficiency: Cas-9 can be directly injected into a cell instead of forcing scientists to go through a breeding process to create mutant subjects, drastically shortening the entire process from 2-3 years to just a few months.
- Multiple mutations: Multiple mutations can be generated into one cell simultaneously, allowing scientists to test more complex models than ever before.
- Modify anything: It’s possible to modify the cells of virtually any animal, including humans. ZNF and TALEN are currently limited to organisms whose DNA is thoroughly understood, namely mice and fruit flies.
- Precision: CRISPR also claims to be more precise. Imagine cutting DNA with scissors versus a scalpel.
What CRISPR can do
One of the most promising and realistic use cases for CRISPR is curing serious diseases in humans, including certain cancers, blood disorders, Huntington’s disease, cystic fibrosis, sickle cell anemia, and more.
CRISPR also has major implications for agriculture. For instance, scientists have already used the technology to render wheat invulnerable to crop-killing agents like powdery mildew. Discoveries such as this could help us feed a hungry world that's expected to reach a population of 9.7 billion by the year 2050.
There’s also been talk of resurrecting extinct animal species. Harvard researchers recently announced their intentions to use CRISPR to do just that with the woolly mammoth. The team is currently experimenting with combinations of elephant and mammoth genes and expect any final result to more closely resemble elephants, but with distinct mammoth features such as smaller ears, a layer of subcutaneous fat, and cold climate-adopted blood.
However, what has been garnering quite a bit of attention—and is arguably the scariest application of this technology—is the idea of augmented humans or designer babies. In other words, CRISPR can be used to alter the human genome in a way that creates individuals with advanced intelligence and desirable physical attributes.
There are of course serious ethical considerations that should and must be addressed when it comes to altering the human genome in this way. For example, we could end up with a dystopia of superhumans, with "enhancements" only available to those who can afford them. Additionally, scientists could make a mistake in the process, resulting in the introduction of new diseases that could be passed on for generations.
CRISPR is already making headway in the agriculture space, and scientists are finding more and more use cases for the technique every day. Yet, even if scientists and CRISPR supporters successfully alleviate moral concerns and obtain government and regulatory approval, we're still about 20 years away from leveraging the technology for human use.
However, one thing remains certain: CRISPR’s potential is both undeniable and incredibly exciting.
Sources: Reuters, Nature, MIT, Wired, and The Guardian.