AP Biology class blog for discussing current research in Biology

Tag: #CRISPR/Cas9 (Page 1 of 2)

GATTACA is Here!

            In August of 2017 Scientists finally had figured out how to successfully edited genes in human embryos in order to treat serious disease-causing mutation using advanced CRISPER/Cas9. This is a  major milestone as it brings scientists closer to the reality of being able to genetically engineer babies in order to re


Photo by J Levin W

pair faulty genes. This concept has always been feared due to the lack of success and safety of previous genetic tests, however, this study proves that scientists can now successfully edit genes.“We’ve always said in the past gene editing shouldn’t be done, mostly because it couldn’t be done safely,” said Richard Hynes, a cancer researcher at the MassachusettsInstitute of Technology who co-led the committee. “That’s still true, but now it looks like it’s going to be done safely soon,” he said, adding that the research is “a big breakthrough.” Genetic testing has also been regarded as unethical due to the possibility of eugenics, in which wealthy families would pay to have their embryos adjusted to get enhanced cosmetic traits such as height and muscle mass. “What our report said was, once the technical hurdles are cleared, then there will be societal issues that have to be considered and discussions that are going to have to happen. Now’s the time.” This successful study has come out only months after a national scientific committee recommended new guidelines for modifying embryos in which they strongly urge gene editing be used solely for severe hereditary medical conditions.

Crispr-Cas9 is the gateway to a new frontier in genetic engineering. Here’s The good and the bad.

For a number of years now, molecular biologists have been diving increasingly further into the field of genome editing. The latest development into the field is the emergence of CRISPR-Cas9. CRISPR-Cas9 has risen to prominence over other potential methods of genome editing due to its relatively simple construction and low cost. CRISPR-Cas9’s original primary and intended purpose was to help fix mutations within DNA, and with this it could theoretically help eradicate entire diseases. This application of CRISPR is wholly positive, however with the increasing prevalence of the technique other potential uses have been discovered, and some of these potential uses raise profound ethical questions.

One of the main concerns of people skeptical about CRISPR is their assertion that once the door to the wholesale genetic editing of offspring is open, there is no going back. This, on its own, is a reasonable concern. The ability to choose a child’s sex, eye color, hair color and skin complexion is very likely to be made available to by CRISPR in the coming years. CRISPR does not yet have the capability to influence more abstract elements of the genome, such as intelligence and athletic ability, but this may not be far off. There are legitimate concerns that this is a slippery slope towards a dystopian society similar to the one seen in the movie Gattaca, where society is stratified into two distinct classes: those who are genetically engineered and those who are not.

Another concern raised by some scientists is the overall safety of genetic editing. A potentially very hazardous negative result of CRISPR is the possibility of an “off target mutation.” An off target mutation is the result of CRISPR mutating something other than the intended part of the genome and it could have disastrous consequences. Now, many scientists believe that with further advancements in the field the likelihood of something like an off target mutation occurring could be reduced to almost zero. However, it is important to examine the risks of any new process, and the prospect of something like an off target mutation occurring is certainly noteworthy.

For more information click here.

What does the future hold for CRISPR-Cas9?

Genome editing, or the technologies in which scientists can change the DNA of an organism, is on the rise, especially with its latest development, CRISPR-Cas9, the most efficient method of all of the methods to edit DNA.

Like many other discoveries in science, CRISPR-Cas9 was discovered through nature. Scientists learned that certain bacteria capture snippets of DNA from invading viruses, making DNA segments called CRISPR arrays, helping them remember the virus to prepare for future invasions of that virus. When they are confronted with that virus again, RNA segments from the CRISPR arrays are created which target the DNA of the virus, causing the enzyme Cas9 to cut the virus’ DNA apart, which would destroy the virus.


We use the same method in genome editing with CRISPR-Cas9 by creating RNA that binds to a specific sequence in a DNA strand and the Cas9, causing the Cas9 to cut the DNA at that specific sequence. Once this is done, the scientists create a sequence to replace the one that was cut to get the desired genome.

This technology is most prominently used to attempt to treat diseases, where the somatic cells’ genomes are altered which affect tissues, as well as prevent genetic diseases where the sperm or egg’s genome is changed. However, the latter causes some serious ethical concerns of whether we should use this technology to enhance human traits. But this begs the question that if we start using it more and more to prevent genetic diseases, will this open the door for it to be used in new ways?

CRISPR Cas9, too good to be true?

After its peak in popularity following its reveal as a possible “genetic modifier” in 2013, the CRISPR Cas-9 enzyme system has been the center of debate within the biology community. Thought to be the solution to all genetic and hereditary diseases by simply “cutting out” the fault gene, new research and studies have shown that a majority of people (65 to 79 percent) have antibodies that would fight cas-9 proteins.

“The study analyzed blood for antibodies to two bacteria from which Cas9 is derived: Streptococcus pyogenes and Staphylococcus aureus. The researchers’ concern stemmed from the fact that these bacteria frequently cause infections in humans, and so antibodies to them may be in our blood” states

While the overall effects are unclear, the study concludes that the result would be “significant toxicity” and an unsafe use of the gene editing tool.

What do you think? Is the current risk of using Cas-9 worth the reward?

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Cas9, photo by J LEVIN W


Potential cure to ALS, the disease that inspired the ice bucket challenge!

You all remember the ALS ice bucket challenge, that took social media by storm, in which people dumped ice water on their heads in order to raise money and awareness to ALS, a neurodegenerative disease that progressively destroys the motor neurons and eventually leads to death.


There is currently no cure to this horrible disease. However new genetic technology (CRISPR) may change all that.

In short, CRISPR is a new form of gene editing that allows scientists to change an organism’s DNA.

Scientists discovered that ALS is caused by a mutation in the C9orf72 gene. ALS is often caused by a significant repeat of a segment of DNA that becomes toxic. So, using CRISPR, scientists deducted which genes either protect against or cause these toxic DNA segments. This process was extremely effective and scientists found about 200 genes that affect ALS. For example, scientists found a gene that codes for a protein called Tmx2 that when removed from mice neurons caused the mice to survive whereas not removing them killed them. This means that scientists are beginning to figure out how to cure ALS.

Discoveries such as these are revolutionary as we can now find specific causes for previously fatal, cureless diseases  such as this. In addition, using this technology we can target these specific genes and save lives.

However, whenever we discuss gene editing we must ethically consider when does this become too far? Where is the line between helping to cure people and helping to destroy society by designing babies?

To answer my own question, I think it is crucial that we take any step possible to help find cures in situations such as this. That being said, there are clear limits that must be respected. The line is definitely hazy. Let me know in the comments your thoughts about gene editing!

But for now, let’s enjoy this scientific win and hope that ALS can be officially cured. Good job ice bucket challenge for bringing attention to a serious issue that may now actually be cured.

Original Article:

Inside Out

CRISPR is a revolutionary tool used for editing the human genome. It allows for the altering of  any given DNA sequence and ability to modify any one specific genes’ function. Its applicability consists of correcting genetic defects, treating and preventing the spread of diseases, and improving crops. However, it also raises some ethical concerns, that of which mainly is the idea that practicing CRISPR technology could be considered as playing the role of “God”.

CRISPR was adapted from the natural defense mechanisms of bacteria, which use CRISPR-derived RNA and Cas proteins, to prevent attacks by viruses and other intruding organisms. They do so by chopping up and destroying the DNA of the virus. When these components are derived and applied to more complex, organisms, it allows for the manipulation of genes.

Disregarding its ethical concerns, CRISPR can provide substantial support to a previously uncharted area of medicine; the diagnosing and treating of genetic disorders, which was previously thought to be that if one had a genetic disorder it would be incurable.  Clinical trials are set to take place both in Europe and in North America, where patients with rare genetic disorders will give cellular samples in an attempt to alter their genome, implant them back into the individual, and hopefully cure the genetic abnormality.

With CRSPR taking such progressive strides in the past year, it is not outrageous to predict what its usage could end up providing society with.  With the ability to edit the human genome there are endless possibilities in which science could evolve this area of study to benefit the human race.  CRISPR can even be used to boost the expected intelligence of an embryo.  Who knows, thirty years from now we could be watching the news and hear of the first ever “superhuman”, a genetically modified human that has been hand-coded for optimality in all human functions.


The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)and CRISPR-associated protein 9 complex has become one of the biggest technological advances in science. This genome editing technology has taken multiple advances toward closer research into studies of embryonic development to cancer. CRISPRainbow, a modification to CRISPR where the Cas9 is mutated, allows researchers to label up to seven different genomic locations in live cells.
CRISPR has been used for editing genomes, however, research specialist Hanhui Ma and his team has used it to label DNA and track the movement of DNA in live cells. With this new research, we can find the precise genomic location in order to understand the movement of chromosomes. This is important because the genes that create our biological make-up and control our health do so by their location in the 3-D space.
Currently, with CRISPR, we can only label three genomic locations at a time in each cell. It has extremely challenged scientists to label more sites because it would require cells to be mixed in formaldehyde, which would kill them, making it impossible to observe the chromosome’s structure when stimulated by a response.
The new Cas9 mutation causes the nuclease to deactivate, so it only binds to DNA and doesn’t cut the genome. Then, the CRISPRainbow is docked into location by the guide RNA which can be programmed technologically. Research specialist, Hanhui Ma was able to figure out a way to implement computational coloring. Each guide RNA would include one of the three primary fluorescent proteins: red, green or blue which then can be observed in real time under a microscope. Pretty cool, right? Well, guess what? It doesn’t stop here. Ma decided to go even further in his research and attach a second fluorescent protein to the guide RNA. Ma could then combine the three primary colors to generate three additional labels: cyan, magenta, and yellow. From the primary colors, he was able to achieve white as the seventh color.
CRISPRainbow can track the challenging and dynamic movement of genomes that may lead to biological consequences. Research Scientist, Hanhui Ma, states “With this technology, we can visualize different chromosome loci at different points in time.” We can observe the structural changes in chromosomes overtime with help us understand their relation to health and disease. So why do you think they called is CRISPRainbow? What kind of diseases can we track with this new technology? What more can CRISPRainbow do in the near future?

CRISPR used to treat diabetes, kidney disease, muscular dystrophy

Scientists have now created a new method of using CRISPR genome editing, which would allow them to activate genetics without breaking the DNA. It could potentially be a major improvement in using gene editing techniques to treat human diseases. Currently, most of the CRISPR systems work by creating DSBs or Double strand Breaks in regions of the genome targeted for editing. Many scientists and researchers have opposed creating breaks in the DNA of living humans. So the Salk group tried their new method to treat diseases such as diabetes, kidney disease, and muscular dystrophy in the mouse models.

CRISPR has proved to be a powerful tool for gene therapy, but there are still many concerns regarding some mutations generated by the DSBs though the Salk group is able to get around that concern. Originally, Cas9 enzyme couples with guide RNA to create DSBs. But just recently, researchers have used a dead form of dcas9 to stop the cutting of DNA. DCas9 would couple with transcriptional activation domains, that turn on targeted genes. But it is still difficult to be used in clinical applications.

Salk group team combined dcas9 with bunch of activator switches to uncover a combination that would work even when the proteins are not fused with one another. These components all work together to influence endogenous genes. It would influence genetic activities without having to change the DNA sequence.

In order to prove the usefulness of this method, scientists used mouse models of acute kidney disease, type 1 diabetes, and a form of muscular dystrophy. They engineered their new CRISPR system to boost the expression of an endogenous gene that would reverse the symptoms of the disease. In all three cases, they reversed disease symptoms.

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Photo credit: Martyn Fletcher


CRISPR: Back at it Again

Researchers at the Gladstone Institutes made scientific history by turning skin cells of rats into stem cells by activating a certain gene in those cells using CRISPR technology. CRISPR technology is a tool used for editing genomes through making it easy for researchers to modify gene function and easily alter DNA sequences. CRISPR stands for “clusters of regularly interspaced short palindromic repeats” and it has been a popular topic of discussion and research in the science world.

Gladstone senior investigator, Sheng Ding and his team shaped their research aiming to answer the question; “can you reprogram a cell just by unlocking a specific location of the genome?” which they answered yes at the end. They decided to test on specific stem cells that can be turned into any cell type in the body, Pluripotent cells. Ding built upon a different senior investigators discovery, Shinya Yamanaka, who found he could make stem cells out of skin cells by treating skin cells with four key proteins called transcription factors. Here Yamanaka learned that the transcription factors could change which genes are expressed in the cell, turn off genes associated with skin cells, and turn on genes associated with stem cells and he called these skin turned to stem cells Induced Pluripotent Stem Cells (iPSC).

So Sheng Ding was inspired by Yamanaka’s investigation and decided to follow the same process but treat skin cells with CRISPR  instead of transcription factors. They targeted genes Sox2 and Oct4, only expressed in stem cells, which can turn on stem cell genes and turn off those associated with different cell types. With CRISPR, Ding and his team discovered they could reprogram cells activating Sox2 or Oct4. This proved to be more efficient than previous study, as using the CRISPR technology to target a specific location on the genome immediately triggered a natural chain reaction reprogramming the entire cell into an iPSC.

This was surprising and groundbreaking for this research group as they answered their guided question but came out with more. They still want to understand how the CRISPR technology was able to trigger a change within a whole cell efficiently and immediately compared to any other tested process. This study expanded knowledge on CRISPR and its many functions, and creates more questions on why and how it can do what it does. CRISPR technology continues to confuse scientists by manipulating genes in new, different, and unpredictable ways so the next question is, what does it have up its sleeve next???

Original Article 

Hacking Evolution to Stop Malaria?

Kevin Esvelt is a biochemist, at MIT Media Lab, his approach to dealing with disease is instead of waiting for a disease to infect you, eradicate it completely. His hope is that on animals, such as mosquitos. he could use the CRISPR technology to block the gene. He believes that “we should be able to build organisms that are programmed to be immune to every virus known to infect them“.  By using the CRISPR/Cas9 gene editing and gene drive he, and his team, would be able to block that gene from appearing in the next generation.



Although, eradicating horrible diseases such as Ebola and Malaria sounds extremely beneficial; there is some draw back. Malaria, for example, is spread across many nations; therefor, scientist would need permission to genetically alter a species from each nation; but before this can be agreed upon test communities would need to be set up. Esvelt would want to test the CRISPR technology in small, localized areas before moving on to an entire species. Esvelt is confident that with a disease as deadly as Malaria, nations would be able to reach an agreement to go with gene editing. Esvelt hopes that by using CRISPR technology he would be able to create organisms, like mosquitos, in the case of Malaria, that are programmed to be immune to Malaria. If this were to happen these deadly disease would not be able to spread. Hence, Esvelt’s key belief of not waiting for the disease infect you, but rather eradicate it completely,



Transporting Organs from Pigs to People!

The shortage of human organs for transplants is one of the biggest problems facing the medical field, about 22 people die on waitlists for organs die every day in the United States. But there is a newfound hope! A recent discovery using CRISPR-cas9 gene editing may address this challenge.

Scientists have been dreaming about transplanting organs from pigs into people for years, a process called xenotransplantation, but they have been held back by threatening viruses in the pigs DNA called PERVs. PERVs are present throughout the pig genome and would infect a person who receives a pigs heart, lung, kidney, etc. This infection could be fatal and may cause a human epidemic. Scary right? However, scientists at well-known laboratories had a breakthrough this past summer using CRISPR-cas9 and created healthy pigs with no traces of PERV genes!

It was, in fact, the two early developers of that gene-editing technology, Harvard University’s George Church, and Luhan Yang, who first believed CRISPR’s guide RNA and a DNA-slicing enzyme could make precise, genome-wide changes to pig cells. Their results showed that CRISPR could “knock out” PERV genes at all 62 sites in the pig genome. However, there were some flaws in their experiments, they used a line of “immortal” pig kidney cells, which were chosen for their ability to survive in the dish. Earlier the team had tried to use genetically “normal” pig cells, but once the cells were edited they failed to grow normally. Yang says, “CRISPR’s hacking job of the DNA may have prompted them to stop dividing or self-destruct.” But when they exposed the cells to a “chemical cocktail” making them “immortal,” the growth of PERV free cells in the dish rose to 100%.  The next step was to actually produce piglets. The researchers inserted DNA containing the nuclei of the edited cells into the eggs taken from the ovaries of pigs in a slaughterhouse. They allowed each egg to develop into an embryo and implanted it in the uterus of a surrogate mother. Boom, healthy, PERV-free piglets!

After this huge finding, Church and Yang co-founded a company called eGenesis which focuses on the engineering of transplant organs and projects in laboratories around the world exploded. Currently, a transplant surgeon at the University of Maryland is gearing up to swap a pig heart into the chest of a baboon! However, obstacles still remain in regard to humans; the rejection of the organs once in humans, the physiological incompatibility, how to insert genes that will prevent toxic interactions with human blood, and (what I believe is most important) the ethical question.





CRISPR, A Cure to Heart Disease?

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     While CRISPR‘s full potential in the department of gene editing is still being researched, scientists have just successfully discovered CRISPR’s ability to correct a defective gene that causes a certain type of heart disease. Though scientists are unclear as to the type of gene corrected in order to cause this change, this discovery was made for the first time in the United States, by an experiment done on live human embryos. However the new information yielded from this experiment is extremely beneficial as it shows CRISPR’s potential in correcting genetic errors that cause disease, as well as in human embryos meant for pregnancy.

Another reason for which this study particularly stands out in its importance, is because it is much different from the other developments scientists have made in CRISPR’s abilities. Studies have been conducted worldwide using CRISPR to edit of somatic cell’s gnomes, however, this only affects individual people. This study (also done by researchers in China), has been done by editing germ line cells, which result in changes that are passed down through every following generation.

However since the changes made to cells do affect all generations that follow, scientists are unsure of the exact effects of this new technique. Although it seems that this technology will be very beneficial in stopping harmful genetic diseases, it can also be used for changing DNA to genetically determine the eye colors, height or even mental and physical abilities and intelligence. This new phenomenon is own as “designer babies”, and for many reasons, this is not something that the United States is trying to use CRISPR’s abilities for. For this reason, United States has recently created more severe guidelines regarding gene editing technology, as well as enforcing CRISPR’s use on embryos only for prevention of harmful genetic diseases, when other treatments were not successful – as a last resort – formed by the National Academies of Sciences, Engineering and Medicine.

In the study done, scientists edited out a mutant copy of MYBPC3, using CRISPR. MYBPC3 is a gene that encodes a protein that creates well maintained and structured heart muscles. Hypertrophic cardiomyopathy, known as HCM, are caused by mutations in that gene, and cause spontaneous cardiac arrest. This occurs in even the youngest and healthiest of athletes, affecting 1 in 500 humans.

In this study, the mother was carrying the normal version of a gene, while the father had the mutant gene. Using CRISPR, the scientists were able fix the mutant version, by cutting and replacing the DNA. Directly after they placed the fertilized egg in a petri dish, while introducing the genome editing parts at the same time. The results of this process proved to be very effective, as 75% of the embryos showed no mutant genome. Without the use of CRISPR when egg fertilization occurred, the chances of mutation would have been present in 50%!

From these results the researchers came to the conclusion that they have realized the potential for mosaicism. Mosaicism is when only some of the cells are edited and the rest are not affected, which results in some normal cells, as well as some mutant cells. The scientists have also gathered the effects of off-targets. Off targets are the CRISPR edited genes that appear to look like mutant genes, but are actually not. Within this study, one egg fertilized from 58 showed mosaicism, and there was no detection of effects from off-targets. Theseare very impressive results, due to the fact that both of these possible situations can cause limitations in effectiveness and safety.

Though researchers need to do over this experiment many times in order to soliditfy the effectiveness of this study for the future, if they want to use this on eggs intended for pregnancy, as the eggs fertilized in the study were not meant for pregnancy… However, the results have yielded nothing but good news for the future of CRISPR technology (besides, the risk in advancements in “designer babies”, which couldchange the future of conceiving, forever…). This article was extremely interesting for me to read, as I am very interested in studying Biology in the future, or even pursuing a track to medicine. Perhaps, I may get the chance to even experiment with CRISPR at some time in my life, as it becomes a growing presence throughout the science world!

Primary Source Article: U.S. researchershave used gene editing to combat heart disease in human embryos

If You Want the Bull, Take its Horns

Everyone loves milk. It’s the foundation of Ice Cream, it’s an essential component in any good bowl of cereal, it’s the foundational ingredient in the creamy center that unites the Oreo, and pro tip: you can put chocolate syrup in it (I thought of that; I call it “ChocoLeche” I think it could really catch on).


Before I continue, I’d like to take a moment of silence for those cursed by the demon known commonly as lactose intolerance. Your lives are a miserable nightmare that I don’t even want to think about. #findacure .


Like I said everyone loves milk, and everyone knows it comes from cows. Few people however are aware of the fact that the cow that produces milk is different than the cow that produces the much beloved meat products such as steak and hamburgers. The Cows that are used for meat are of the Angus variety. The Cows for dairy products are Holstein Cows. One major difference that used to exist between the two is that Holstein, or dairy cows, had horns, unlike the meatier Angus cows which did not have horns. Thanks to Crispr-Cas9, scientists from UC Davis lead by Dr. Alison Van Eenennaam have rid Holstein cows of their horns, and in doing so have granted dairy cows everywhere with a higher quality of life.


Photo by

U.S. Department of Agriculture

The first question that needs to be answered is why would this be important. Why does it matter that we got the horns off of Holsteins? It’s important first because these horns put cows at risk from each other. Cows with horns might advertently or inadvertently use them to injure themselves, other cows or their handlers. Many previously solved this problem by dehorning the cows, which involves burning the horns off and is extremely painful for the cows. Without horns to begin with no cows need to be dehorned and fewer cows are injured. As Dr. Jeff Burkhardt puts it “From the animal welfare perspective, Dr. Alison Van Eenennaam’s research is worthy of high praise: The prospect of reducing the pain associated with de-horning, which itself was introduced to eliminate risks of animals hurting themselves and others, is exactly the kind of thing that animal scientists should be doing” – Jeff Burkhardt. The Ethics of Gene editing in general is a complex and hotly debated issue right now due to the novelty of the CRISPR system, however, in this instance I feel as though the researchers are on very sound moral ground. They have made a change that safely and indisputably decreases the pain a dairy cow experiences. If you disagree I’d invite you to burn two holes in the side of your head, and reconsider whether you’re comfortable bestowing that treatment on another living creature.

The second question is how did they do this. The answer is deceptively simple. As I formerly noted, Angus cows do not possess horns. What they do possess is a gene that prevents the growth of a horn. The group of researchers at UC Davis first identified this gene and its cause. They then used CRISPR-Cas9 to cut it out of an Angus Cow’s DNA and inserted it into the DNA of a Holstein cow. The Angus cow gene prevents horn growth in Holstein cows, and the Holstein cows officially became a GMO, or genetically modified organism. A GMO that no longer has horns.


CRISPR/Cas9, Omnipotent Cure or New Toy for the Rich and Famous?

Editing the human genome has been a highly controversial subject matter in the field of bioethics as advancements with techniques like CRISP/Cas9 allow for precise DNA cutting and sequence addition.  As of February 14th, a panel for the National Academies of Sciences and Medicine concluded that altering DNA in gametic cells is ethical as long as it is only utilized to cure genetic diseases that could be passed down to offspring and not to simply enhance health or certain characteristics.  This is novel as former recommendations given by organizers of a global summit on human gene editing proposed that gene manipulation via molecular scissors should not be used in the production of babies.  However, it is important to note that while the Nation Academies reports often impact policy formation in the United States and around the world, they hold no actually legislative weight and authority rests in hands of Congress, regulatory agencies like the FDA, and both state and local governmental bodies.

Depiction of CRISPR/Cas9 protein complex by Thomas Splettstoesser, source

Some scientists like panel cochair Alta Charo of the University of Wisconsin-Madison Law School are still highly skeptical of heritable gene editing and have not yet pinpointed times when it is just to perform.  “We are not trying to greenlight heritable germline editing,” says Charo, “We’re trying to find that limited set of circumstances where its use is justified by a compelling need and its application is limited to that compelling need.  We’re giving it a yellow light.”  Others hold the notion that any manipulation of the germline will inevitably culminate in the creation of “designer babies”.  In their minds, this could stigmatize disabled people, heighten inequality between the rich and those who can’t afford the treatment, and possibly start a new wave of eugenics like seen in the sci-fi film Gattaca (1997). Marcy Darnovsky, executive director of the Center for Genetics and Society in Berkeley, California, comments, “Once you approve any form of human germline modification you really open the door to all forms.”

On the other end of the spectrum, many are thrilled with the decision and see a bright future for the human race.  Sean Tipton, a spokesman for the American Society for Reproductive Medicine in Washington, D.C., states, “It looks like the possibility of eliminating some genetic diseases is now more than a theoretical option.  That’s what this sets up.” Indeed, debilitating diseases caused by mutations in single genes like cystic fibrosis and Huntington’s could become a thing of the past in the near future.  Unfortunately, genome editing to cure more complex diseases and disorders associated with mutations in multiple genes (autism, schizophrenia, etc.) is still very far in the future.

In reality, there is little to worry about in the area of germline editing for now as panelist Jeffrey Kahn of Johns Hopkins University ensures that the beginning of heritable gene alteration is closed off until requirements can be met at the legislative level.  Additionally, the panel presented numerous obstacles that must be cleared before germline manipulation can become a reality.  Nita Farahany, a bioethicist at Duke Law School claims, “Some people could read into the stringency of the requirements to think that the benefits could never outweigh the risks.”  Also, the requirement to follow up with multiple generations of genetically modified children to study what consequences the therapy holds for future offspring is an invasion of privacy.  Farahany adds that, “You can’t bind your children and grandchildren to agree to be tracked by such studies.”  On top of all this, it is extremely difficult to draw distinctions between therapies and enhancements. George Church, a Harvard University geneticist, remarks that nearly all medical advancements could be considered life-enhancing.  “Vaccines are advancements over our ancestors. If you could tell our ancestors they could walk into a smallpox ward and not even worry about it, that would be a superpower.”

So, where will germline editing take the species Homo sapiens?  Is the cure for cancer on the horizon?  Would the pursuit of creating perfect humans be beneficial or harmful for society?

More CRISPR Improvements

Crispr-Cas9 is a genome editing tool that is creating a whole lot of buzz in the science world. It is the newest faster, cheaper and more accurate way of editing DNA.  Crispr- Cas9 also has a wide range of potential applications. It is a unique technology that enables geneticists and medical researchers to edit parts of the genome by cutting out, replacing or adding parts to the DNA sequence.  The CRISPR-Cas9 system consists of two key molecules that introduce a mutation into the DNA. The first Molecule is an enzyme called Cas9. Cas9 acts as a pair of scissors that can cut the two strands of DNA at a specific location in the genome so that bits of DNA can be added or removed.  The second is a piece of RNA called guide RNA or gRNA. This consists of a small piece of pre-designed RNA sequence located within a longer RNA scaffold. The scaffold part binds to DNA and the pre-designed sequence guides Cas9 to the right part of the genome. This makes sure that the Cas9 enzyme cuts at the right point in the genome.Screen Shot 2016-04-10 at 4.50.55 PM

CRISPR-Cas9 is efficient compared to previous gene-editing techniques, but there’s still plenty of room for improvement. CRISPR is less efficient when employing the cellular process of homology-directed DNA repair, or HDR, as opposed to nonhomologous end joining.  Jacob Corn, the scientific director of the Innovative Genomics Initiative at the University of California, Berkeley, and his colleagues have come up with a way to improve the success rate of homology-directed repair following CRISPR-Cas9. “We have found that Cas9-mediated HDR frequencies can be increased by rationally designing the orientation, polarity and length of the donor ssDNA to match the properties of the Cas9-DNA complex,” the researchers wrote in their paper, “We also found that these donor designs, when paired with tiled catalytically inactive dCas9 molecules, can stimulate HDR to approximately 1%, almost 50-fold greater than donor alone.”

“Our data indicate that Cas9 breaks could be different at a molecular level from breaks generated by other targeted nucleases, such as TALENS and zinc-finger nucleases, which suggests that strategies like the ones we are using can give you more efficient repair of Cas9 breaks,” coauthor Christopher Richardson, a postdoc in Corn’s lab, said in a statement.

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HIV Resistance to CRISPR/Cas9

A recent study, described in the Science Daily, shows that researches who used the CRISPR/Cas9 to mutate HIV-1 within cellular DNA found that the mutation led to unexpected resistance.

When HIV enters a cell, its RNA genome is converted into DNA and becomes intertwined with the cellular DNA. So the goal for the CRISPR/Cas9 is to target a DNA sequence and cleave viral DNA. The problem is HIV is too good at surviving and thriving despite new mutations, making it more difficult for the CRISPR/CAS9 to target.


Photo Source

Chen Liang, Senior Investigator at the Lady Davis Institute at the Jewish General Hospital, noted that when they sequenced the viral RNA of escaped HIV, they were surprised to see that majority of the mutations the virus had, instead of resulting from the errors of viral reverse transcriptase, were rather introduced by the cellular non-homologous end joining machinery when repairing the broken DNA.

The mutations to the sequences caused by the HIV were unrecognizable to the Cas9. Thus the resistant viruses just continued to replicate.

This study serves as a cautionary tale for scientists hoping to apply CRISPR/Cas9 as an antiviral. Liang does not believe these efforts are useless, however, as he is hopeful about strategies that could overcome this roadblock. One such strategy would be to target multiple sites with CRISPR/Cas9 or use other enzymes besides Cas9. After the solution is identified, the next step will be figuring out ways to deliver the treatment to patients. Liang is confident that CRISPR/Cas9 will open doors for finding a cure for HIV-1 and many other viruses.

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How CRISPR/Cas9 could one day prevent AIDS

CRISPR/Cas9 is a new gene editing tool that can target and modify DNA with great accuracy.  This new tool has many scientific uses, including treatment of many diseases.  Recently, several breakthroughs have been made in treating HIV with CRISPR Cas9.  However, a number of issues with the tool have come up at the same time.

To understand how CRISPR eliminates HIV, one must know how HIV replicates. HIV replicates by taking over a host cell and injecting its RNA into the cell.  This RNA becomes DNA and joins together with parts of the host cell’s DNA.  After entering the cells, the virus can lay dormant for several years, but will eventually start replicating and taking over other cells.  The standard form of treatment for HIV is an antiretroviral.  While antiretrovirals can be very effective at limiting the spread of the disease, it cannot fully remove it or stop it forever.

HIV virus

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The CRISPR Cas9 could potentially be used to inhibit the spread of HIV by editing the virus out of a cell’s DNA.  Researchers at The University of Massachusetts Medical School have been developing a technology to perform this impressive task.  While there have been several successful trials in preventing HIV from spreading, several trials have lead to increased resistance for the HIV.

“When we sequence the viral RNA of escaped HIV, the surprise is that the majority of the mutations that the virus has are nicely aligned at the site where Cas9 cleaves the DNA, which immediately indicates that these mutations, instead of resulting from the errors of viral reverse transcriptase, are rather introduced by the cellular non-homologous end joining machinery when repairing the broken DNA,” says Chen Liang, a senior investigator at the Lady Davis Institute at the Jewish General Hospital and the Associate Professor of Medicine at the McGill University AIDS Centre.

These mutations alter the strand of DNA, preventing the CRISPR Cas9 from recognizing it.  If the CRISPR Cas9 cannot recognize the virus, it cant remove the viral DNA, allowing the virus to create more copies of itself.  Despite these limitations, researchers like Liang are confident that they can succeed.


CRISPR/Cas9 Provides Promising Treatment for Duchenne Muscular Dystrophy

There are nine kinds of muscular dystrophy and of these, Duchenne MD is the most common severe form of childhood MD. It affects about 1 in 5000 newborn males, only in very rare cases has it affected females. DMD is a genetic disorder that causes progressive muscle degeneration and weakness. Patients usually die by age 30 to 40.

DMD is caused by the absence of a protein, dystrophin, that helps keep muscle cells intact. In 1986 it was discovered that there was a gene on the X chromosome that, when mutated, lead to DMD. Later, researchers discovered that the protein associated with this gene was dystrophin. From this information, we can tell that this disorder is sex-linked, which explains why women are mainly carriers.

No one has found an absolute cure for this genetic disorder until now. Even in recent years, people have discovered treatments that will make patients’ lives more bearable, but never reverse the disorder. As a result of these advances, mostly in cardiac and respiratory care, patients are able to live past teen year and as long as in to their fifties, though this is rare. Although there are still drugs being tested like Vamorolone (a “dissociative steroid,” is an anti-inflammatory compound), more treatments on the molecular level are now being considered. However, thanks to recent discoveries and research with the new genetic technology, CRISPR/ Cas9, scientists may have found a treatment for DMD.

This new approach to gene correction by genome editing has shown promise in studies recently. This particular correction can be achieved in a couple ways: one is by skipping exon 51 of the DMD gene using eterplirsen (a morpholino-based oligonucleotide). Studies over four years show prolonged movement abilities, and a change in the rate of decline compared to controls. The newest approach to gene correction using CRISPR/Cas9, which the article I’m writing about focuses on, was performed in this study as next described: the CRISPR/Cas9 system targets the point mutation in exon 23 of the mdx mouse that creates a premature stop codon and serves as a representative model of DMD. Multiple studies in three separate laboratories have provided a path and laid the groundwork for clinical translation addressing many of the critical questions that have been raised regarding this system. The labs also discovered by further demonstrations, that this is a feasible treatment for humans. Functional recovery was demonstrated in the mice, including grip strength, and improved force generation- all of which are very important and hopeful discoveries. It is estimated from these studies that this new method will pass clinical trials and go on to benefit as many as 80% of DMD sufferers. Even greater success rates are expected if this is performed in young and newborn DMD patients.

A Cure to HIV is Near, But Not Here Yet

The study of genetics, specifically gene editing, has taken monumental leaps over the past few years. One of the biggest achievements of late is the discovery and further research into CRISPR/Cas9. Being able to use CRISPR/Cas9 to edit the genome sequences of living cells far has been the efficient tool geneticists have dreamed of. However, a recent study proved that CRISPR/Cas9 is not yet able to work as the perfect antiviral mechanism.

Image courtesy of AJC,

Image courtesy of AJC,

Scientists from McGill University, the University of Montreal, the Chinese Academy of Medical Sciences and Peking Union Medical College did a study where CRISPR/Cas9 was inserted to the replicative process of the HIV invested cell. After HIV enters a cell it’s RNA is converted to DNA which attaches to a cell’s pre-existing strand of DNA. This is when CRISPR/Cas9 is used, it breaks up these two DNA strands. The study found that many of the targeted viruses were killed, however the others viruses developed mutations on even just one nucleotide that made them more resistant and impossible for Cas9 to identify. In conclusion, scientists realize they may need to target more than one region of the DNA at once to effectively kill viruses like HIV.

This topic is very interesting to me because it reflects how we are on the cusp of some incredible biological achievements. I am particularly interested in this study because the effect of HIV/AIDs has devastated not only our country, but also the world, and this study seems like an important step in finding the cure that could save millions of lives. CRISPR/Cas9 seems to offer amazing possibilities, and this is one specific area that grabbed my attention. Do you think a solution to currently incurable diseases is near? Why/Why not? Let me know in the comments below.



Crispr 9, A Dangerous New Field


Crispr 9 Editing

With the new developments in gene altering, scientists have begun to use technology to alter the gene sequence of embryos. According to an article by Tia Ghost, Chinese scientists have modified the genes of human embryos with mixed results. The idea behind the research was that they would cut out a faulty gene in the DNA sequence and replace it with a correct one, therefore improving the embryo. This is done through a stretch of RNA called CRISPR targets places on the genome that are then cut by Cas9, an enzyme that cuts out specific strands of DNA leaving a spot to be filled within the genome. Scientists then provide a new strand of DNA as replacement. This method is effective in all different kinds of animals as well as humans.

However, the technology is not yet accurate enough to become common practice. According to a leading scientist in the field “the CRISPR technology is simply too risky to use in embryos” at this point. The issue arises in the fact that the RNA sometimes goes to a different site then the one desired, slicing out a necessary part of the genome and replacing it with useless information. This could lead to harmful mutations in the embryo, the opposite of what the scientists want. Even if the technology was at a higher level, editing embryos is still a large ethical dilemma. Some scientists feel that they should not alter life, but simply let it play out the same way it has for billions of years. Other’s argue that each child deserves the best possible chance they can get. Both have strong arguments, and only time will tell which side will win out.




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