We've Sequenced the Human Genome. So Why Haven't We Cured More Diseases? | Discover Magazine2/24/2020 Good evening all,
In class, we have talked a number of times about how our phenotype (our physical appearance and characteristics) stems from our genotype (the particular set of alleles that we have in our genome). We've also considered how phenotype and genotype are related, by examination of a handful of traits which are influenced (all, or mostly) by individual genes (such as the trait for freckles, or attached earlobes). These examples allow us to evaluate the relationship between alleles (such as dominant and recessive forms), to consider patterns of gamete formation and potential crosses (via Punnett squares), and to assess familiar patterns of inheritance (via pedigrees). These relatively straightforward examples suggest that other aspects of our genetic health, such as disease risk for a variety of conditions, might also be similarly simple: easy to diagnose, and potentially easy to fix, if problematic. Alas, this is not the case for most traits of human disease concern. I'm forwarding here a link to an article which nicely describes why the genetic basis of our health is not so straightforward, or easy to manipulate. In reality, most of our important human diseases are only very weakly linked to individual genes, which themselves may play only a very small role in influencing our individual disease risk or expression. https://www.discovermagazine.com/health/weve-sequenced-the-human-genome-so-why-havent-we-cured-more-diseases So, of what value then is this massive Human Genome Project, this effort to sequence, and understand, every single one of our genes? Well, in short, we do not yet know its full value, as we are still learning how to mine this enormous database. It seems very likely to yield important insights into our genetic disease risks, but it has not led to the immediate creation of a broad spectrum of ready, easy-to-use, off-the-shelf treatments for our human diseases. That day of individualized, genetic approaches to health is coming, though - the first individually-based genetic treatments are now in use. They are as yet not broadly proven, and they remain enormously expensive. But, they represent proof-of-concept types of studies, which suggest that, as our knowledge and technology improve, the days of the 'genome card' are coming. Save some space in your wallets... Have a great evening - Dr. Nealen
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Good evening all,
Week after recent week, the global spread and impact of the new 'Wuhan' coronavirus continues to dominate our science and health news. Most health experts appear to have underestimated how easily this virus would spread, how long it it would persist, and how damaging it would be for global functions like travel and commerce. In terms of its lethality, this coronavirus is far less dangerous than the seasonal influenza (the "flu") that we experience each winter here in the U.S., which typically is associated with 3-10x as many deaths annually in this country alone than have been attributed to the Wuhan coronavirus worldwide. Still, this Wuhan coronavirus (more specifically, Covid-19 coronavirus) is a very good demonstration of the fact that infectious diseases do not have to be especially lethal to be very problematic. Given the scale of disruption this virus has caused, it is no surprise that a variety of treatment and preventative efforts are underway, including attempts to develop effective screens for infected persons, as well as tests of potential immunizations to prevent the contraction of the disease. One of the less well-publicized efforts is the attempt to identify "patient 0" - the first human to "catch" the virus. Of what value would it be to find this first human subject? In theory, this would allow scientists their best hope of finding the original source of the virus, the animal species from which the virus made its leap to human hosts. Identification of the animal host reservoir (be it bat, snake, pig, or other) could help limit future spread of the virus, and may also inform biological efforts to combat it. The more we know about the virus, the better our chances to counter it. But, there may be drawbacks to finding "patient 0", as outlined in this recent article: https://www.bbc.com/future/article/20200221-coronavirus-the-harmful-hunt-for-covid-19s-patient-zero Is there more harm to be done, or more gain, in finding this first human subject? Experts disagree, but not yet to the point at which the search for this first subject will cease. Finding the original subject in a disease outbreak is a standard epidemiological technique, and there are plenty of examples (including several described in this article) in which finding that first human host of a new disease agent was helpful. Still, the article also describes the risk of stigmatization, and error - what if someone is wrongly identified as the starting point for an epidemic? In this country, and in other developed nations, there are relatively standardized procedures for dealing with newly emerging diseases. When a new pathogen or new disease begins to spread that eclipses scientific expectations, however, some of the cracks in our defenses begin to show, and efforts to combat the new condition often become less uniform than would be ideal. We are seeing exactly this in recent weeks: there is open debate about how to count the number infected by this virus, continued uncertainty over its origins, and newly emerging evidence of how spectacularly unsuccessful quarantine efforts can be. We still have much to learn, it seems. The good news is that the virus really is of relatively minor risk to healthy individuals. We've no nearby cases here in Western PA, but should it appear, remember that the best defenses are surprisingly simple: avoid contact with infected individuals, and wash your hands well with soap after public forms of contact. Common sense is equal to best practice, in this case. Have a great evening - Dr. Nealen Good morning all,
I'm passing along here (at page bottom) a link to a recent news article about genetic sleuthing of the source for the 'Wuahn coronavirus', the virus that appears to have made its first appearance in humans and now is causing tens of thousands of infections, and perhaps >1,000 deaths, worldwide. As you now, this has been the top genetics and health news story for several weeks now. Viruses are a bit of an evolutionary quandary. They are tiny objects, composed of protein and nucleic acid. They are not considered to be cells, and they are not considered to be 'alive'. They are parasitic 'replicating devices' - they can only replicate when they have successfully infected the cell of a host species. And, they are designed to take-over the protein machinery of their host's cell, causing it to make many more virus particles, and to spread them. https://en.wikipedia.org/wiki/Virus Mammals have evolved with viruses throughout our history, and our immune systems contain some viral defenses, just as our genomes contain bits and pieces of DNA that may have been viral in origin. In recent years and decades, we have increasingly been aware of 'new' viruses, not previously seen in humans, that are suddenly causing human disease. Swine flu, avian flu, MERS, SARS, and others - and now, the Wuhan coronavirus. Why are viruses so common in mammals? Because we are really good hosts for them - lots of cellular protein machinery, warm-blooded cells which promote high rates of viral replication, dense social structure which promotes transmission. From rats to cats, bats, camels and more, each mammalian group bears its own viral load. Why do viruses move between mammal species? Two words: mutation and opportunity. As viruses mutate, they can gain or lose features that make them better, or worse, suited for particular host species (e.g., cats versus dogs). As species co-mingle, the odds improve that a virus can successfully 'make the leap' to a host of a different species, one to which it is newly well-suited. Why are so many of these novel viruses originating in Asia? Population density and food production practices. On the global scale, the U.S. is relatively sparsely populated (save our largest cities). Across the globe, it is very common for population densities to be much higher than those found here. And, high human densities require ramped-up food production. Much of food production here is commercialized and removed from the public, but again, this is a global exception. Across most of the world, food production tends to be on a smaller scale, and it tends to be much more personal - individuals tending their own animals, working with their tissues and bringing their own products to open market. Together, this density and close contact ups the risk of transmission of animal viruses to human hosts. This article describes genetic efforts to identify the original animal source of the human virus, as well as to characterize the virus more fully. The more we know about the virus, the more likely we can stop the spread of infections and develop effective preventatives (such as a vaccine) and treatments. https://www.sciencemag.org/news/2020/01/mining-coronavirus-genomes-clues-outbreak-s-origins I will occasionally pass along articles of this type during the semester. My purpose in doing so is to help you to become more aware of topics at the interface of biology and society, and also to help you assess how you obtain your science and health news. Those of us working in science obtain our scientific news, quite often, directly from the original sources: the people conducting the studies and reporting the results. They publish their findings in science journals, or present them at conferences. Most people do not obtain their news directly, but hear news via secondary sources, such as news releases from scientific organizations, or news stories from the major news outlets. These secondary reports often are then carried by tertiary outlets (smaller/other reporting sources). Along the way from source to audience, science news is normally distilled (a lot) - much of the detail is excluded or simplified, and the reports often are boiled-down to singular take-home messages, which may (or may not) be good representations of the original work. When you browse the links that I will forward, or when you access science and health news on your own, I'd encourage you to delve a little bit deeper into them, to read more than just the summaries, and to follow links back to original sources when possible. I'd also encourage you to think a little about the translation of news from source to consumer, and the reputability of the news outlets that you use. You will not be formally tested on any of the material in the news stories that I will send you, but I do hope that the material in them makes its way into our classroom conversations. Have a great weekend - Dr. Nealen Avian flu! Swine flu! Now, bat flu? Last week I sent you a news article on the recent coronavirus, first described in Wuhan, China, that was emerging as a 'new' human virus, one not previously detected in humans or known to cause human disease. A week later, as you know, this remains the top health news story, and rightly so - the virus has now killed many dozens, and infected many thousands, around the globe. Viruses are a bit of an evolutionary quandary. They are tiny objects, composed of protein and nucleic acid. They are not considered to be cells, and they are not considered to be 'alive'. They are parasitic 'replicating devices' - they can only replicate when they have successfully infected the cell of a host species. And, they are designed to take-over the protein machinery of their host's cell, causing it to make many more virus particles, and to spread them. https://en.wikipedia.org/wiki/Virus Mammals have evolved with viruses throughout our history, and our immune systems contain some viral defenses, just as our genomes contain bits and pieces of DNA that may have been viral in origin. In recent years and decades, we have increasingly been aware of 'new' viruses, not previously seen in humans, that are suddenly causing human disease. Swine flu, avian flu, MERS, SARS, and others - and now, the Wuhan coronavirus. https://www.bbc.com/news/health-51237225 Why are viruses so common in mammals? Because we are really good hosts for them - lots of cellular protein machinery, warm-blooded cells which promote high rates of viral replication, dense social structure which promotes transmission. From rats to cats, bats, camels and more, each mammalian group bears its own viral load. Why do viruses move between mammal species? Two words: mutation and opportunity. As viruses mutate, they can gain or lose features that make them better, or worse, suited for particular host species (e.g., cats versus dogs). As species co-mingle, the odds improve that a virus can successfully 'make the leap' to a host of a different species, one to which it is newly well-suited. Why are so many of these novel viruses originating in Asia? Population density and food production practices. On the global scale, the U.S. is relatively sparsely populated (save our largest cities). Across the globe, it is very common for population densities to be much higher than those found here. And, high human densities require ramped-up food production. Much of food production here is commercialized and removed from the public, but again, this is a global exception. Across most of the world, food production tends to be on a smaller scale, and it tends to be much more personal - individuals tending their own animals, working with their tissues and bringing their own products to open market. Together, this density and close contact ups the risk of transmission of animal viruses to human hosts. What can we do? Addressing the inequities of education and opportunity that put some more at risk of public health diseases than others is a global problem, one that is daunting in scale. Can we immediately correct it? No, of course not. We can, however, be careful consumers, paying attention to the kinds of products we purchase, their degree of commercialization, the level of exploitation that may be attached to them. We can pay attention to climate issues, which seem to exacerbate many emerging diseases. And personally, we can practice good public health ourselves - stay up-to-date with vaccinations, follow good hand hygiene protocols, cover our coughs and our sneezes. And, we can stay informed, and help others to be informed - that is perhaps the best defense of all. I hope that, by this time next week, the spread of this coronavirus has been contained. Sincerely, Dr. Nealen |
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