What Is CRISPR and What Is It Really Capable Of?
A DNA editing technique called CRISPR continues to hit the news, one after another in medicine. In theory, CRISPR can find any problematic region in DNA, cut it out, and replace it with a new set of nucleotides. But in real life, this cut and paste job is not always easy.
Like many other biotechnological methods, CRISPR was invented by bacteria and creatively reworked by scientists. Bacterial cells can contain strangely repetitive patterns of DNA (“short palindromic repeats grouped at regular intervals”) that turn out to be the notebook of viruses and other enemies that the bacteria has already fought and defeated. With this information, proteins like Cas9 (“linked to CRISPR [protein] 9”) can find these intruders the next time they appear. This protein performs a search and destroy mission based on a piece of DNA from a scrapbook.
In the laboratory, scientists can customize this system to search for any DNA sequence they like, including in our own genes. What if we could repair a defective gene in someone, for example, with a genetic disorder? The possibilities of CRISPR are enormous .
But CRISPR is also a new technology, and it’s not magic. Researchers need to find flaws in CRISPR-based approaches. For example, we can’t use CRISPR on humans until we know it’s safe. And it can be tricky to implant CRISPR molecules into all cells where their target DNA actually lives. So here’s your reality check of what new technologies are actually capable of.
Criminals don’t use it to evade DNA detection
If criminals can be found through DNA databases , then perhaps an enterprising killer can alter the DNA in his body so that it no longer matches the samples they left at the crime scene. (The Daily Mail reported that one scientist suggested that this is possible.) Good idea, but the big problem with CRISPR is actually getting the DNA editing technology to be delivered to all the cells it needs to reach. We do not currently know if CRISPR can process all cells in the human body.
This Twitter thread by Leila Katirai describes some of the other issues. Forensic DNA tests examine many different places in the genome, so you will need to make many different CRISPR changes. DNA tracked in forensic databases is also difficult to deal with from a biochemical point of view. And even if you could change your genome, you would want to check if you succeeded (hard or cheap job) before offering some blood to the police.
Bottom line: won’t happen anytime soon.
You probably won’t be able to build muscle either.
What if you don’t want to change all of your DNA, but just tweak something a little for cosmetic purposes? Biohacker Josiah Zayner injected the CRISPR recipe into his arm to block a gene called myostatin. Babies with a natural defect in this gene are born like tiny bodybuilders because they have little to no myostatin to inhibit their muscle growth. However, changing a gene in an adult’s cells does not necessarily lead to the same thing.
Even when the researchers conducted the CRISPR experiment to block myostatin in 35 dog embryos , only two pups were born with the desired mutation. And these two … well, they don’t quite look like dog carcasses.
Bottom line: seems unlikely.
There is hope for a cure for the disease
CRISPR for adults is facing serious challenges, but trials are likely to begin this year. Research teams from Europe and the United States plan to treat beta-thalassemia and sickle cell anemia in this way. They plan to extract the patients ‘own hematopoietic stem cells, use CRISPR to repair the defect in the DNA of those cells, and then reintroduce the cells into the patients’ bodies. Conceptually, it is similar to a bone marrow transplant, except that each person is their own donor.
Bottom line: Promising, but it’s too early to tell if this will work.
CRISPR Crops May Become New GMOs
Many of the crops we grow today have been modified from their original wild counterparts. In some cases, this is due to a natural mutation that occurred millennia ago. In other cases, people controlled the fate of their favorite plants by choosing which plants or animals to breed with each other. And in recent decades, we have been able to work directly with the DNA of living beings.
Certain techniques have come to be known as genetic engineering, and the plants thus obtained are known as GMOs or genetically modified organisms. (Despite some negative press coverage, GMOs are no better or worse for you than their non-GMO counterparts .)
GMO crops have additional levels of government regulation beyond what “traditional” plants have to deal with. But this year, the USDA ruled that CRISPR crops will not be considered GMOs unless they contain foreign DNA . So, for example, if you take corn and add the gene of another living thing, it can be considered GMO. But if you just use CRISPR to remove a gene without adding anything new, the law considers it the equivalent of breeding a new corn variety the old fashioned way.
But the FDA announced that it is considering CRISPR in animals as a form of gene therapy , which means it is regulated as a veterinary drug. Therefore, if you want to use CRISPR to produce a hornless cow orpurebred dog that lacks one of the harmful mutations that often occur with inbreeding , you will have to go through the extremely expensive process of approving it as a new drug.
Bottom line: CRISPR plants may appear in a grocery store near you in a few years, but animals edited with CRISPR face big hurdles.