About 50% of South Asians and 16% of Europeans carry gene cluster associated with respiratory failure after SARS-CoV-2 infection and hospitalization
Clinical pathology laboratories and medical laboratory scientists may be intrigued to learn that scientists from two research institutes in Germany and Sweden have determined that a strand of DNA associated with a higher risk of severe COVID-19 in humans is similar to the corresponding DNA sequences of a roughly 50,000-year-old Neanderthal from Croatia.
The researchers concluded that this gene cluster—passed down from Neanderthals to homo sapiens—triples the risk of developing severe COVID-19 respiratory symptoms for some modern day humans.
In a press release, Pääbo said, “It is striking that the genetic heritage from the Neanderthals has such tragic consequences during the current pandemic. Why this is must now be investigated as quickly as possible.”
Might Useful Biomarkers for Clinical Laboratory Tests Be Identified?
Though it is not immediately clear how these findings may alter current approaches to developing treatments and a vaccine for the SARS-CoV-2 coronavirus, it is another example of how increased knowledge of human DNA leads to new understandings about genetic sequences that can spur development of useful biomarkers for clinical laboratory diagnostics tests.
Swedish geneticist Svante Pääbo, PhD (above right), Director of the Max Planck Institute for Evolutionary Anthropology in Germany, is co-author of a recent study that traced a gene cluster linked to a higher risk of severe COVID-19 to 50,000-year-old Neanderthals from Croatia. “It is striking that the genetic heritage from the Neanderthals has such tragic consequences during the current pandemic,” he said. Nevertheless, such discoveries sometimes lead to new biomarkers for clinical laboratory tests and diagnostics. (Photo copyright: Max Planck Institute for Evolutionary Anthropology.)
This latest research reveals that people who inherit a specific six-gene combination on chromosome 3—called a haplotype—are three times more likely to need artificial ventilation if they are infected by the SARS-CoV-2 coronavirus. Yet, the researchers can only speculate as to why the gene cluster confers a higher risk.
“The genes in this region may well have protected the Neanderthals against some other infectious diseases that are not around today. And now, when we are faced with the [SARS-CoV-2] coronavirus, these Neanderthal genes have these tragic consequences,” Pääbo told the Guardian.
According to the study, the gene risk variant is most common in South Asia where about half of the population carries the Neanderthal risk variant. In comparison, one in six Europeans have inherited the gene sequence and the trait is almost nonexistent in Africa and East Asia.
“About 63% of people in Bangladesh have at least one copy of the disease-associated haplotype, and 13% have two copies (one from their mother and one from their father). For them, the Neandertal DNA might be partially responsible for increased mortality from a coronavirus infection. People of Bangladeshi origin living in the United Kingdom, for instance, are twice as likely to die of COVID-19 as the general population,” Science News reported.
Other Research Connecting Genes to Severe COVID-19 Symptoms
The haplotype on chromosome 3 first made headlines in June when the New England Journal of Medicine (NEJM) published the “Genomewide Association Study of Severe COVID-19 with Respiratory Failure,” which analyzed COVID-19 patients in seven hospitals in Italy and Spain. The researchers found an association between the gene cluster on chromosome 3 and severe symptoms of SARS-CoV-2 after infection and hospitalization. The study also pointed to the potential involvement of chromosome 9, which contains the ABO blood-group system gene, indicating that humans with type A blood may have a 45% higher risk of developing severe COVID-19 infections.
However, Mark Maslin, PhD, Professor of Climatology at University College London, cautions against drawing strong conclusions from the initial research tying disease risk to the genetic legacy of Neanderthals, the Guardian reported. He suggested that, while the Neanderthal-derived variant may contribute to COVID-19 risk in certain populations, genes are more likely to be just one of multiple risk factors for COVID-19 that include age, gender, and pre-existing conditions.
“COVID-19 is a complex disease, the severity of which has been linked to age, gender, ethnicity, obesity, health, virus load among other things,” Maslin told the Guardian. “This paper links genes inherited from Neanderthals with a higher risk of COVID-19 hospitalization and severe complications. But as COVID-19 spreads around the world it is clear that lots of different populations are being severely affected, many of which do not have any Neanderthal genes.
“We must avoid simplifying the causes and impact of COVID-19, as ultimately a person’s response to the disease is about contact and then the body’s immunity response, which is influenced by many environmental, health and genetic factors.”
Andre Franke, PhD, Director of the Institute of Clinical Molecular Biology, Kiel University in Germany, agrees with Maslin, the Associated Press reported. In a statement “ahead of the study’s final publication,” he said these latest findings have no immediate impact on the treatment of COVID-19, and he questioned “why that haplotype—unlike most Neanderthal genes—survived until today,” AP reported.
All of this deepens the mystery of the SARS-CoV-2 coronavirus. Genomics research continues to add new insights into what is known about COVID-19 and may ultimately provide answers on why some people contract the disease and remain asymptomatic—or have mild symptoms—while others become seriously ill or die. Understanding why and how certain genes increase the risk of severe COVID-19 could give rise to targeted clinical laboratory tests and therapies to fight the disease.
‘Prime editing’ is what researchers are calling the proof-of-concept research that promises improved diagnostics and more effective treatments for patients with genetic defects
Known as Prime Editing, the scientists developed this technique as a more accurate way to edit Deoxyribonucleic acid (DNA). In a paper published in Nature, the authors claim prime editing has the potential to correct up to 89% of disease-causing genetic variations. They also claim prime editing is more powerful, precise, and flexible than CRISPR.
The research paper describes prime editing as a “versatile and precise genome editing method that directly writes new genetic information into a specified DNA site using a catalytically impaired Cas9endonuclease fused to an engineered reverse transcriptase, programmed with a prime editing guide RNA (pegRNA) that both specifies the target site and encodes the desired edit.”
And a Harvard Gazette article states, “Prime editing differs from previous genome-editing systems in that it uses RNA to direct the insertion of new DNA sequences in human cells.”
Assuming further research and clinical studies confirm the
viability of this technology, clinical laboratories would have a new diagnostic
service line that could become a significant proportion of a lab’s specimen
volume and test mix.
In that e-briefing we wrote that Liu “has led a team of scientists in the development of a gene-editing protein delivery system that uses cationic lipids and works on animal and human cells. The new delivery method is as effective as protein delivery via DNA and has significantly higher specificity. If developed, this technology could open the door to routine use of genome analysis, worked up by the clinical laboratory, as one element in therapeutic decision-making.”
Now, Liu has taken that development even further.
“A major aspiration in the molecular life sciences is the ability to precisely make any change to the genome in any location. We think prime editing brings us closer to that goal,” David Liu, PhD (above), Director of the Merkin Institute of Transformative Technologies in Healthcare at the Broad Institute, told The Harvard Gazette. “We’re not aware of another editing technology in mammalian cells that offers this level of versatility and precision with so few byproducts.” (Photo copyright: Broad Institute.)
Cell Division Not Necessary
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. It is considered the most advanced gene editing technology available. However, it has one drawback not found in Prime Editing—CRISPR relies on a cell’s ability to divide to generate desired alterations in DNA—prime editing does not.
This means prime editing could be used to repair genetic mutations in cells that do not always divide, such as cells in the human nervous system. Another advantage of prime editing is that it does not cut both strands of the DNA double helix. This lowers the risk of making unintended, potentially dangerous changes to a patient’s DNA.
The researchers claim prime editing can eradicate long lengths of disease-causing DNA and insert curative DNA to repair dangerous mutations. These feats, they say, can be accomplished without triggering genome responses introduced by other forms of CRISPR that may be potentially harmful.
“Prime editors are more like word processors capable of
searching for targeted DNA sequences and precisely replacing them with edited
DNA strands,” Liu told NPR.
The scientists involved in the study have used prime editing to perform over 175 edits in human cells. In the test lab, they have succeeded in repairing genetic mutations that cause both Sickle Cell Anemia (SCA) and Tay-Sachs disease, NPR reported.
“Prime editing is really a step—and potentially a significant step—towards this long-term aspiration of the field in which we are trying to be able to make just about any kind of DNA change that anyone wants at just about any site in the human genome,” Liu told News Medical.
Additional Research Required, but Results are Promising
Prime editing is very new and warrants further
investigation. The researchers plan to continue their work on the technology by
performing additional testing and exploring delivery mechanisms that could lead
to human therapeutic applications.
“Prime editing should be tested and optimized in as many cell types as researchers are interested in editing. Our initial study showed prime editing in four human cancer cell lines, as well as in post-mitotic primary mouse cortical neurons,” Liu told STAT. “The efficiency of prime editing varied quite a bit across these cell types, so illuminating the cell-type and cell-state determinants of prime editing outcomes is one focus of our current efforts.”
Although further research and clinical studies are needed to
confirm the viability of prime editing, clinical laboratories could benefit
from this technology. It’s worth watching.
Use of synthetic genetics to replicate an infectious disease agent is a scientific accomplishment that many microbiologists and clinical laboratory managers expected would happen
Microbiologists and infectious disease doctors are quite familiar with Escherichia coli (E. coli). The bacterium has caused much human sickness and even death around the globe, and its antibiotic resistant strains are becoming increasingly difficult to eradicate.
Now, scientists in England have created a synthetic “recoded” version of E. coli bacteria that is being used in a positive way—to fight disease. Their discovery is being heralded as an important breakthrough in the quest to custom-alter DNA to create synthetic forms of life that one day could be designed to fight specific infections, create new drugs, or produce tools to diagnose or treat disease.
Scientists worldwide working in the field of synthetic genomics are looking for ways to modify genomes in order to produce new weapons against infection and disease. This research could eventually produce methods for doctors—after diagnosing a patient’s specific strain of bacteria—to then use custom-altered DNA as an effective weapon against that patient’s specific bacterial infection.
This latest milestone is the result of a five-year quest by researchers at the Medical Research Council Laboratory of Molecular Biology (MRC-LMB) in Cambridge, England, to create a man-made version of the intestinal bacteria by redesigning its four-million-base-pair genetic code.
The MRC-LMB lab’s success marks the first time a living
organism has been created with a compressed genetic code.
The researchers published their findings in the journal Nature.
“This is a landmark in the emerging field of synthetic
genomics and finally applies the technology to the laboratory’s workhorse
bacterium,” they wrote. “Synthetic genomics offers a new way of life, while at
the same time moving synthetic biology towards a future in which genomes can be
written to design.”
All known forms of life on Earth contain 64 codons—a specific sequence of three consecutive nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis. Jason Chin, PhD, Program Lead at MRC-LMB, said biologists long have questioned why there are 20 amino acids encoded by 64 codons.
“Is there any function to having more than one codon to encode each amino acid?” Chin asked during an interview with the Cambridge Independent. “What would happen if you made an organism that used a reduced set of codons?”
The MRC-LMB research team took an important step toward
answering that question. Their synthetic E. coli strain, dubbed Syn61,
was recoded through “genome-wide substitution of target codons by defined
synonyms.” To do so, researchers mastered a new piece-by-piece technique that
enabled them to recode 18,214 codons to create an organism with a 61-codon
genome that functions without a previously essential transfer RNA.
“Our synthetic genome implements a defined recoding and refactoring scheme–with simple corrections at just seven positions–to replace every known occurrence of two sense codons and a stop codon in the genome,” lead author Julius Fredens, PhD, a post-doctoral research associate at MRC, and colleagues, wrote in their paper.
Science Alert reports that the laboratory-created version of E. coli (above) “isn’t quite a dead ringer for its ancestor. The cells are a touch longer, and they reproduce 1.6 times slower. But the edited E. coli seems healthy and produces the same range and quantity of proteins as the non-edited versions.” (Photo copyright: Jason Chin/STAT.)
Joshua Atkinson, PhD, a postdoctoral research associate at Rice University in Houston, labeled the breakthrough a “tour de force” in the field of synthetic genomics. “This achievement sets a new world record in synthetic genomics by yielding a genome that is four times larger than the pioneering synthesis of the one-million-base-pair Mycoplasma mycoides genome,” he stated in Synthetic Biology.
“Synthetic genomics is enabling the simplification of
recoded organisms; the previous study minimized the total number of genes and
this new study simplified the way those genes are encoded.”
Manmade Bacteria That are Immune to Infections
Researchers from the J.
Craig Venter Institute in Rockville, Maryland, created the first synthetic
genome in 2010. According to an article in Nature,
the Venter Institute successfully synthesized the Mycoplasma mycoides genome
and used it “reboot” a cell from a different species of bacterium.
The MRC-LMB team’s success may prove more significant.
“This new synthetic E. coli should not be able to decode DNA from any other organism and therefore it should not be possible to infect it with a virus,” the MRC-LMB stated in a news release heralding the lab’s breakthrough. “With E. coli already being an important workhorse of biotechnology and biological research, this study is the first time any commonly used model organism has had its genome designed and fully synthesized and this synthetic version could become an important resource for future development of new types of molecules.”
Because the MRC-LMB team was able to remove transfer RNA and
release factors that decode three codons from the E. coli bacteria,
their achievement may be the springboard to designing manmade bacteria that are
immune to infections or could be turned into new drugs.
“This may enable these codons to be cleanly reassigned and
facilitate the incorporation of multiple non-canonical amino acids. This
greatly expands the scope of using non-canonical amino acids as unique tools
for biological research,” the MRC-LMB news release added.
Though synthetic genomics impact on clinical laboratory diagnostics is yet to be known, medical laboratory leaders should be mindful of the potential for rapid innovation in this field as proof-of-concept laboratory innovations are translated into real-world applications.
Expanded ‘Cancer Gene Census’ is expected to accelerate development of new therapeutics and biomarker-based personalized medicine diagnostic tests for disease; could be useful for anatomic pathologists
Oncology is one of the fastest-developing fields in precision medicine and use of DNA-based diagnostics. Surgical pathologists are helping many cancer patients benefit from the use of a companion genetic test that shows their tumors are likely to respond to a specific drug or therapy. Consistent with that work, researchers in the United Kingdom (UK) have now produced the first comprehensive summary of all genes known to be strongly associated with cancer in humans.
The expansion of the “Cancer Gene Census” is noteworthy for anatomic pathologists who should expect to see the information increase the understanding of cancer causes and accelerate the development of new therapeutics and biomarker-based molecular diagnostics.
In this latest Cancer Gene Census, researchers from the Wellcome Sanger Institute (WSI) used CRISPR gene editing systems to produce an expanded catalog of 719 cancer-driving genes in humans.
According to a review article on the project published in Nature Reviews Cancer, “The recent expansion includes functional and mechanistic descriptions of how each gene contributes to disease generation in terms of the key cancer hallmarks and the impact of mutations on gene and protein function.”
The 2018 Cancer Gene Census from the Wellcome Sanger Institute in the United Kingdom summarizes 719 genes suspected of causing cancer in humans and describes how they function across all forms of the disease. (Photo copyright: Wellcome Sanger Institute.)
The Catalogue of Somatic Mutations in Cancer (COSMIC) provided the foundation for the WSI’s research. It involved manually condensing almost 2,000 research papers to develop evidence for a gene’s role in cancer.
While the COSMIC database characterizes more than 1,500
forms of human cancer and types of mutations, the U.K.’s Cancer Gene Census
goes further and “describes which genes are fundamentally involved and
describes how these genes cause disease,” a Wellcome Sanger Institute news
release states.
“For the first time ever, functional changes to these genes
are summarized in terms of the 10 cancer hallmarks—biological processes that
drive cancer,” the statement explains. “Mutations in some genes lead to errors
in repairing DNA, whereas mutations in other genes can suppress the immune
system or promote tumor invasion or spreading. Across the 700 genes in the
Cancer Gene Census, many have two or more different ways of causing cancer.”
Zbyslaw Sondka,
PhD, lead author on the WSI project, believes their study has provided
scientists with much needed new insights. “Scientific literature is very compartmentalized.
With the Cancer Gene Census, we’re breaking down all those compartments and
putting everything together to reveal the full complexity of cancer genetics,” he
noted in a WSI
article.
“This is the broadest and most detailed review of human
cancer genes and their functions ever created and will be continually updated
and expanded to keep it at the forefront of cancer genetics research,” Sondka
added.
Making Precision
Medicine More Precise
An understanding of the roles played by different genes in
various cancers is key to enabling researchers to develop drugs that will be
effective against individual cancers.
“The combination of the Cancer Gene Census with COSMIC will
enable researchers to investigate individual mutations and try to find good
targets for anti-cancer drugs based on the actual processes involved,” Simon Forbes, PhD,
Senior Author of the Cancer Gene Census paper and Director of COSMIC at the
Wellcome Sanger Institute, stated in the WSI news release.
Simon Forbes, PhD (above), Director of COSMIC at the Wellcome Sanger Institute and Senior Author of the Cancer Gene Census paper, believes the institute’s latest Cancer Gene Census, which catalogs 719 cancer-causing genes, will “help make precision medicine even more precise” by allowing “biologists and pharmaceutical scientists to see patterns and target particular pathways with anti-cancer drugs, not solely single genes.” (Photo copyright: Wellcome Sanger Institute.)
The path to precision medicine cancer treatments was further boosted this month when Wellcome Sanger Institute researchers, in partnership with the Open Targets Platform, announced a new system to prioritize and rank 600 drug targets that show the most promise for development into cancer treatments, noted a WSI statement.
The WSI/Open Targets team published its research in the international science journal Nature.
CRISPR-Cas9 and
Personalized Medicine
This latest research springboards off one of the largest CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas9 screens of cancer genes to date. Researchers used CRISPR gene-editing systems to disrupt every gene within 30 different types of cancers and locate several thousand key genes essential for cancer’s survival. They then identified 600 genes that potentially could be used in personalized medicine treatments.
“The results bring researchers one step closer to producing
the Cancer
Dependency Map, a detailed rulebook of precision cancer treatments to help
more patients receive effective therapies,” the Wellcome Sanger Institute statement
notes.
Anatomic pathologists and clinical laboratories should note
the speed at which development of useful biomarkers for diagnosing cancer is
progressing. All labs will want to be prepared to capitalize on those
advancements through the lab testing services they offer in their medical laboratories.
U.S. Patent and Trademark Office will hold hearings to determine whether University of California Berkeley, or Broad Institute of Harvard and MIT, should receive patents for new genomic engineering technique
In the race to master gene-editing in ways that will advance genetic medicine and patient care, one of the hottest technologies is CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats. But now a patent fight has the potential to complicate how pathologists and other scientists use this exciting technology.
This dispute over the CRISPR patent—a tool that has been hailed as one of the biggest biotech breakthroughs of the decade—will likely be settled in the coming months by the United States Patent and Trademark Office (USPTO).
The USPTO will be reviewing key patents awarded for what is called CRISPR/Cas9. The technology is already generating novel therapies for diseases, which should create new opportunities for pathologists and medical laboratories. (more…)
