Genome Reading and Editing Tools for All
An open book representing the ability to read the human genome.
In 2006, the cover of Scientific American was "Know Your DNA" and the inside story was "Genomes for All." Today, we are closer to that goal than ever. Making it affordable for everyone to understand and change their DNA will fundamentally alter how we manage diseases, how we conduct clinical research, and even how we select a mate.
A frequent line of questions on the topic of making genome reading affordable is: Do we need to read the whole genome in order to accurately predict disease risk?
Since 2006, we have driven the cost of reading a human genome down from $3 billion to $600. To aid interpretation and research to produce new diagnostics and therapeutics, my research team at Harvard initiated the Personal Genome Project and later, Openhumans.org. This has demonstrated international informed consent for human genomes, and diverse environmental and trait data can be distributed freely. This is done with no strings attached in a manner analogous to Wikipedia. Cell lines from that project are similarly freely available for experiments on synthetic biology, gene therapy and human developmental biology. DNA from those cells have been chosen by the US National Institute of Standards and Technology and the Food and Drug Administration to be the key federal standards for the human genome.
A frequent line of questions on the topic of making genome reading affordable is: Do we need to read the whole genome in order to accurately predict disease risk? Can we just do most commonly varying parts of the genome, which constitute only a tiny fraction of a percent? Or just the most important parts encoding the proteins or 'exome,' which constitute about one percent of the genome? The commonly varying parts of the genome are poor predictors of serious genetic diseases and the exomes don't detect DNA rearrangements which often wipe out gene function when they occur in non-coding regions within genes. Since the cost of the exome is not one percent of the whole genome cost, but nearly identical ($600), missing an impactful category of mutants is really not worth it. So the answer is yes, we should read the whole genome to glean comprehensively meaningful information.
In parallel to the reading revolution, we have dropped the price of DNA synthesis by a similar million-fold and made genome editing tools close to free.
WRITING
In parallel to the reading revolution, we have dropped the price of DNA synthesis by a similar million-fold and made genome editing tools like CRISPR, TALE and MAGE close to free by distributing them through the non-profit Addgene.org. Gene therapies are already curing blindness in children and cancer in adults, and hopefully soon infectious diseases and hemoglobin diseases like sickle cell anemia. Nevertheless, gene therapies are (so far) the most expensive class of drugs in history (about $1 million dollars per dose).
This is in large part because the costs of proving safety and efficacy in a randomized clinical trial are high and that cost is spread out only over the people that benefit (aka the denominator). Striking growth is evident in such expensive hyper-personalized therapies ever since the "Orphan Drug Act of 1983." For the most common disease, aging (which kills 90 percent of people in wealthy regions of the world), the denominator is maximal and the cost of the drugs should be low as genetic interventions to combat aging become available in the next ten years. But what can we do about rarer diseases with cheap access to genome reading and editing tools? Try to prevent them in the first place.
A huge fraction of these births is preventable if unaffected carriers of such diseases do not mate.
ARITHMETIC
While the cost of reading has plummeted, the value of knowing your genome is higher than ever. About 5 percent of births result in extreme medical trauma over a person's lifetime due to rare genetic diseases. Even without gene therapy, these cost the family and society more than a million dollars in drugs, diagnostics and instruments, extra general care, loss of income for the affected individual and other family members, plus pain and anxiety of the "medical odyssey" often via dozens of mystified physicians. A huge fraction of these births is preventable if unaffected carriers of such diseases do not mate.
The non-profit genetic screening organization, Dor Yeshorim (established in 1983), has shown that this is feasible by testing for Tay–Sachs disease, Familial dysautonomia, Cystic fibrosis, Canavan disease, Glycogen storage disease (type 1), Fanconi anemia (type C), Bloom syndrome, Niemann–Pick disease, Mucolipidosis type IV. This is often done at the pre-marital, matchmaking phase, which can reduce the frequency of natural or induced abortions. Such matchmaking can be done in such a way that no one knows the carrier status of any individual in the system. In addition to those nine tests, many additional diseases can be picked up by whole genome sequencing. No person can know in advance that they are exempt from these risks.
Furthermore, concerns about rare "false positives" is far less at the stage of matchmaking than at the stage of prenatal testing, since the latter could involve termination of a healthy fetus, while the former just means that you restrict your dating to 90 percent of the population. In order to scale this up from 13 million Ashkenazim and Sephardim to billions in diverse cultures, we will likely see new computer security, encryption, blockchain and matchmaking tools.
Once the diseases are eradicated from our population, the interventions can be said to impact not only the current population, but all subsequent generations.
THE FUTURE
As reading and writing become exponentially more affordable and reliable, we can tackle equitable distribution, but there remain issues of education and security. Society, broadly (insurers, health care providers, governments) should be able to see a roughly 12-fold return on their investment of $1800 per person ($600 each for raw data, interpretation and incentivizing the participant) by saving $1 million per diseased child per 20 families. Everyone will have free access to their genome information and software to guide their choices in precision medicines, mates and participation in biomedical research studies.
In terms of writing and editing, if delivery efficiency and accuracy keep improving, then pill or aerosol formulations of gene therapies -- even non-prescription, veterinary or home-made versions -- are not inconceivable. Preventions tends to be more affordable and more humane than cures. If gene therapies provide prevention of diseases of aging, cancer and cognitive decline, they might be considered "enhancement," but not necessarily more remarkable than past preventative strategies, like vaccines against HPV-cancer, smallpox and polio. Whether we're overcoming an internal genetic flaw or an external infectious disease, the purpose is the same: to minimize human suffering. Once the diseases are eradicated from our population, the interventions can be said to impact not only the current population, but all subsequent generations. This reminds us that we need to listen carefully, educate each other and proactively imagine and deflect likely, and even unlikely, unintended consequences, including stigmatization of the last few unprotected individuals.
Catching colds may help protect kids from Covid
A new study shows that the immune system's response to colds can help prepare it to defend against COVID-19 - but only in the very young.
A common cold virus causes the immune system to produce T cells that also provide protection against SARS-CoV-2, according to new research. The study, published last month in PNAS, shows that this effect is most pronounced in young children. The finding may help explain why most young people who have been exposed to the cold-causing coronavirus have not developed serious cases of COVID-19.
One curiosity stood out in the early days of the COVID-19 pandemic – why were so few kids getting sick. Generally young children and the elderly are the most vulnerable to disease outbreaks, particularly viral infections, either because their immune systems are not fully developed or they are starting to fail.
But solid information on the new infection was so scarce that many public health officials acted on the precautionary principle, assumed a worst-case scenario, and applied the broadest, most restrictive policies to all people to try to contain the coronavirus SARS-CoV-2.
One early thought was that lockdowns worked and kids (ages 6 months to 17 years) simply were not being exposed to the virus. So it was a shock when data started to come in showing that well over half of them carried antibodies to the virus, indicating exposure without getting sick. That trend grew over time and the latest tracking data from the CDC shows that 96.3 percent of kids in the U.S. now carry those antibodies.
Antibodies are relatively quick and easy to measure, but some scientists are exploring whether the reactions of T cells could serve as a more useful measure of immune protection.
But that couldn't be the whole story because antibody protection fades, sometimes as early as a month after exposure and usually within a year. Additionally, SARS-CoV-2 has been spewing out waves of different variants that were more resistant to antibodies generated by their predecessors. The resistance was so significant that over time the FDA withdrew its emergency use authorization for a handful of monoclonal antibodies with earlier approval to treat the infection because they no longer worked.
Antibodies got most of the attention early on because they are part of the first line response of the immune system. Antibodies can bind to viruses and neutralize them, preventing infection. They are relatively quick and easy to measure and even manufacture, but as SARS-CoV-2 showed us, often viruses can quickly evolve to become more resistant to them. Some scientists are exploring whether the reactions of T cells could serve as a more useful measure of immune protection.
Kids, colds and T cells
T cells are part of the immune system that deals with cells once they have become infected. But working with T cells is much more difficult, takes longer, and is more expensive than working with antibodies. So studies often lags behind on this part of the immune system.
A group of researchers led by Annika Karlsson at the Karolinska Institute in Sweden focuses on T cells targeting virus-infected cells and, unsurprisingly, saw that they can play a role in SARS-CoV-2 infection. Other labs have shown that vaccination and natural exposure to the virus generates different patterns of T cell responses.
The Swedes also looked at another member of the coronavirus family, OC43, which circulates widely and is one of several causes of the common cold. The molecular structure of OC43 is similar to its more deadly cousin SARS-CoV-2. Sometimes a T cell response to one virus can produce a cross-reactive response to a similar protein structure in another virus, meaning that T cells will identify and respond to the two viruses in much the same way. Karlsson looked to see if T cells for OC43 from a wide age range of patients were cross-reactive to SARS-CoV-2.
And that is what they found, as reported in the PNAS study last month; there was cross-reactive activity, but it depended on a person’s age. A subset of a certain type of T cells, called mCD4+,, that recognized various protein parts of the cold-causing virus, OC43, expressed on the surface of an infected cell – also recognized those same protein parts from SARS-CoV-2. The T cell response was lower than that generated by natural exposure to SARS-CoV-2, but it was functional and thus could help limit the severity of COVID-19.
“One of the most politicized aspects of our pandemic response was not accepting that children are so much less at risk for severe disease with COVID-19,” because usually young children are among the most vulnerable to pathogens, says Monica Gandhi, professor of medicine at the University of California San Francisco.
“The cross-reactivity peaked at age six when more than half the people tested have a cross-reactive immune response,” says Karlsson, though their sample is too small to say if this finding applies more broadly across the population. The vast majority of children as young as two years had OC43-specific mCD4+ T cell responses. In adulthood, the functionality of both the OC43-specific and the cross-reactive T cells wane significantly, especially with advanced age.
“Considering that the mortality rate in children is the lowest from ages five to nine, and higher in younger children, our results imply that cross-reactive mCD4+ T cells may have a role in the control of SARS-CoV-2 infection in children,” the authors wrote in their paper.
“One of the most politicized aspects of our pandemic response was not accepting that children are so much less at risk for severe disease with COVID-19,” because usually young children are among the most vulnerable to pathogens, says Monica Gandhi, professor of medicine at the University of California San Francisco and author of the book, Endemic: A Post-Pandemic Playbook, to be released by the Mayo Clinic Press this summer. The immune response of kids to SARS-CoV-2 stood our expectations on their head. “We just haven't seen this before, so knowing the mechanism of protection is really important.”
Why the T cell immune response can fade with age is largely unknown. With some viruses such as measles, a single vaccination or infection generates life-long protection. But respiratory tract infections, like SARS-CoV-2, cause a localized infection - specific to certain organs - and that response tends to be shorter lived than systemic infections that affect the entire body. Karlsson suspects the elderly might be exposed to these localized types of viruses less often. Also, frequent continued exposure to a virus that results in reactivation of the memory T cell pool might eventually result in “a kind of immunosenescence or immune exhaustion that is associated with aging,” Karlsson says. https://leaps.org/scientists-just-started-testing-a-new-class-of-drugs-to-slow-and-even-reverse-aging/particle-3 This fading protection is why older people need to be repeatedly vaccinated against SARS-CoV-2.
Policy implications
Following the numbers on COVID-19 infections and severity over the last three years have shown us that healthy young people without risk factors are not likely to develop serious disease. This latest study points to a mechanism that helps explain why. But the inertia of existing policies remains. How should we adjust policy recommendations based on what we know today?
The World Health Organization (WHO) updated their COVID-19 vaccination guidance on March 28. It calls for a focus on vaccinating and boosting those at risk for developing serious disease. The guidance basically shrugged its shoulders when it came to healthy children and young adults receiving vaccinations and boosters against COVID-19. It said the priority should be to administer the “traditional essential vaccines for children,” such as those that protect against measles, rubella, and mumps.
“As an immunologist and a mother, I think that catching a cold or two when you are a kid and otherwise healthy is not that bad for you. Children have a much lower risk of becoming severely ill with SARS-CoV-2,” says Karlsson. She has followed public health guidance in Sweden, which means that her young children have not been vaccinated, but being older, she has received the vaccine and boosters. Gandhi and her children have been vaccinated, but they do not plan on additional boosters.
The WHO got it right in “concentrating on what matters,” which is getting traditional childhood immunizations back on track after their dramatic decline over the last three years, says Gandhi. Nor is there a need for masking in schools, according to a study from the Catalonia region of Spain. It found “no difference in masking and spread in schools,” particularly since tracking data indicate that nearly all young people have been exposed to SARS-CoV-2.
Both researchers lament that public discussion has overemphasized the quickly fading antibody part of the immune response to SARS-CoV-2 compared with the more durable T cell component. They say developing an efficient measure of T cell response for doctors to use in the clinic would help to monitor immunity in people at risk for severe cases of COVID-19 compared with the current method of toting up potential risk factors.
In this week's Friday Five: The eyes are the windows to the soul - and biological aging?
Plus, what bean genes mean for health and the planet, a breathing practice that could lower levels of tau proteins in the brain, AI beats humans at assessing heart health, and the benefits of "nature prescriptions"
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on new scientific theories and progress to give you a therapeutic dose of inspiration headed into the weekend.
Listen on Apple | Listen on Spotify | Listen on Stitcher | Listen on Amazon | Listen on Google
Here are the stories covered this week:
- The eyes are the windows to the soul - and biological aging?
- What bean genes mean for health and the planet
- This breathing practice could lower levels of tau proteins
- AI beats humans at assessing heart health
- Should you get a nature prescription?