CRISPR CAS9 Genome Editing

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CRISPR CAS9 Genome Editing could be responsible for a new era of genetically perfected plants, animals, and even humans. A few years ago, something called Clustered Regularly Interspaced Short Palindromic Repeats or CRISPR burst onto the scene. It worked so well that scientists began issuing ethical statements about its use.

CRISPR cuts DNA strands with unprecedented accuracy and simplicity, allowing geneticists to directly edit any of Earth’s organisms however they like. CRISPR could be used to engineer disease-free organisms, formulate high-yield crops, or even cure genetic and hereditary human conditions. Of course, it could theoretically also be used to let parents pick their kid’s sex, eye color, height, or whatever. In the end, CRISPR is, as one Nobel scientist said to the Independent, “jaw-dropping” in its efficiency and simplicity.

How it all began?

It all began in the late 80s when some Japanese scientists were looking at bacterial DNA. They spotted repeated palindromic patterns. A palindrome is a mirrored set of characters (though DNA sequences only use A, C, T, or G). In the 2000s, scientists realized these repeating characters were part of an ancient bacterial immune system! The palindromes were framing the DNA of viral invaders! This viral DNA is used by bacteria’s immune system like a “most-wanted poster!” It would detect an attack, go to the “most wanted poster” section of their DNA, figure out which virus was attacking, and create an RNA defender to fight back.

Now that the RNA knew what to attack it needed a way to do so. Which is where CAS9 comes in. CAS9 or CRISPR associated protein 9 is an enzyme that unwinds DNA and cuts it up. Now, the trick is, that cutting process works with more than just viral DNA. Once scientists figured out the process, they learned how to use it to cut out and replace any DNA sequence. I know it’s confusing but think of it as our own immune system. The RNA is like antibodies, tagging the invaders, and the CAS9 eliminates them as our white blood cells do. Except instead of the cellular level it’s on the molecular level. That’s tiny.

How Could It Edit Your DNA?

crispr-cas91-CRISPR CAS9 Genome Editing

After word got out, scientists everywhere began to make their own RNA targets, wrap them in CAS9 and send them out to cut DNA. Like our own private RNA army. CRISPR-CAS9 is so accurate it can recognize a few as 20 base-pairs, meaning scientists could cut single genes out of a DNA strand. After it’s cut, the strand self-repairs, disabling the gene. But, if scientists inject replacement DNA it fills the space instead. This allows us to swap in DNA wherever we like. Want corn with genes to fight bacteria? Cool. Want fish that glow? Grab some DNA from phosphorescent algae and toss it in there. This technique is so simple, it’s scary. It’s paving the way for widespread genetic engineering, and it’s kicked off a media frenzy. Like when Chinese authorities announced they’d edited human embryos, though they did not allow them to grow.

Craig Mello is the co-Laureate of the 2006 Nobel Prize for medicine and he told The Independent, “It’s a triumph of basic science,” and claimed it was even more important than the discovery that had won him the Nobel Prize. But because it is so simple, scientists are calling for ethical oversight, and the need to align science with “public support.” Now, CRISPR CAS9 genome editing isn’t perfect. Sometimes the process will target the wrong section of DNA and cut there. But a new paper in Nature describes how scientists altered the CAS9 enzyme reducing “off-target mutations to undetectable levels.” So, they improved on evolution, and now it’s perfect. And even more super scary.

Our Body Could Be Immune to CRISPR

A lot of hay has been made about CRISPR CAS9 Genome Editing technique. It’s opened the possibility of chopping and swapping DNA. The implications are huge for humans and our genome. We could alter the genes of embryos or treat genetic maladies in those already born. Clinical trials on humans are scheduled to start for the first time. But just as they are getting underway, there may be a problem due to our immune system.

To understand why our immune system is being a jerk and preventing us from treating disorders like sickle-cell anemia, it helps to step back and remember exactly what CRISPR CAS9 is. It’s actually an immune response bacterium use to protect themselves from viruses. CAS9 is a protein the bacteria make that act like molecular scissors, cutting virus DNA to ribbons, and two of the most commonly used types of CAS9 come from bacteria that can cause staph infections or strep throat. These are bacteria we want our immune systems to have a defense against. And to defend against them, our immune system has to be able to recognize the bacteria and the various proteins they make, so they can track them down and destroy them.

Also Read: All About Oumuamua

The immune system is just doing what comes naturally. To see if these two versions of CAS9 were on our immune system’s hit list, researchers tested the blood of 34 donors for antibodies. They found 65 percent had a defense against the strep version while 79 percent fought the staph variety. In another experiment with 13 blood donors, 6 of them had T-cells that attacked staph’s CAS9. The findings are yet to be peer-reviewed, but one of the authors is the scientific founder of a leading CRISPR human therapy company, so he’s got some credibility. And if our immune systems respond to CRISPR, it could mean more than just rendering the therapy ineffective. It could make our immune systems go haywire and kill us, which has happened in a previous attempt at human genetic therapy.

Is this the end of the line for CRISPR?

There are already a few solutions to this possible problem, like modifying the CRISPR CAS9 Genome Editing technique into a form our immune system can’t recognize:

  • Using a different protein from the oodles of other bacteria that have their own versions of CAS9.
  • If the protein gets attacked when it’s in our bodies, then perhaps we could put it to work outside our bodies, modifying extracted cells before returning them to the body.
  • CAS9 could be used in places where the immune system is locked out, like inside our eyes where it could treat hereditary blindness.

CRISPR has way too much potential to let a little thing like our bodies stop progress. The findings of these recent experiments are more of a speed bump than a brick wall. Medical advances occasionally have to overcome biological defenses. For example, our blood vessels in our brains make it really hard to deliver medicine to our old noodle.

What if CRISPR CAS9 Genome Editing Backfires?

With all the storm about CRISPR CAS9 Genome Editing in the news, it may feel like using it to pick your kids eye-color is just around the corner. But this seemingly miraculous gene-editing technology may not actually be as simple or as safe as we thought. Just so we are all on the same page, CRISPR (or more accurately CRISPR CAS9 Genome Editing) works by cutting the DNA of a cell at a designated spot. Say a section of DNA that represents a certain gene. Then, when the cell tries to repair the damaged DNA, it often ends up just disabling the gene altogether. This has all kinds of uses. Maybe we want to turn off a gene that produces too much of a certain protein. CRISPR can do that. Say we want to see what a certain gene even does? CRISPR can help us do that too.

Is it promising for treating inherited disorder?

crispr-cas9-2-CRISPR CAS9 Genome Editing

Ever since it was first used to edit living cells in 2013, CRISPR has been touted as a promising technology for treating inherited disorders, cancer, and other diseases with no current treatment options. Teams of researchers around the globe had even hoped to begin human trials. In China, researchers have been working with CRISPR in humans since 2016. No results from these trials have been published so far. The first human trial of CRISPR gene-editing as a treatment for cancer has begun in the US as reported by NPR.

Several new studies released in the last few years suggest we need to be more cautious when editing the human genome. Two of these studies found that when CRISPR performs its hallmark trick and cuts DNA, that damage can kill the cell, or make it stop growing. CRISPR modifications are also less likely to kill cells that have a defective version of a gene called P53. P53 plays a role in preventing the onset of cancer by regulating a cell’s life cycle. So, by leaving more of the defective cells alive than healthy ones, CRISPR may be inadvertently raising the risk of cancer in that patient. Which is, like, the opposite of the goal. And we haven’t even gotten to the most recent study that raises concerns.

Also Read: What is Neuromorphic Computing?

Up until now, CRISPR CAS9 Genome Editing’s cutting function has been accurate in the specific area of interest–the spot in the DNA that’s supposed to be cut. But that’s because researchers were only looking for mutations caused by CRISPR in the immediate vicinity of the cut. New research reveals that in about 20% of cells, CRISPR results in much larger deletions than we thought. Up to more than 100 base pairs. Researchers did not notice this before because they were looking for harmful mutations and didn’t see any. But that’s because the entire region was gone.

In CRISPR treatments that would target billions of cells inside the human body, this could lead to, again a risk of cancer. Putting us right back at square one. So, where do we go from here? CRISPR CAS9 Genome Editing permanently alters your genome. So, we want to make sure we get it right before we make moves in real human bodies.

Updates:

  • CRISPR CAS9 Genome Editing of plants and animals gets the green light in Australia. Under Australia’s gene technology law research to breed animals like pigs using gene editing won’t necessarily be regulated. Its regulation will be more relaxed than New Zealand and Europe but tighter than the US. Food authority yet to decide to the label of gene-edited foods and on safety assessment.
  • CRISPR CAS9 Genome Editing helps in the discovery of deadly box jellyfish antidote. Researchers at the University of Sydney have found an antidote to the fatal sting delivered by the most venomous animal on earth—the Australian box jellyfish.


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