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Is there a justifiable need for diseases to exist?

Is there a justifiable need for diseases to exist?

30/04/2018
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Merogenomics


Diseases can be caused by a variety of biological events, but I bet very few of us have thought about the retrotransposons contributing to disease development. Probably very few of us even know what that means! After all, the only identifiable part of this word is the root retro, like a blast from the past, which is perhaps very fitting, as you will soon find out.

Image of Merogenomics article quote on how are viruses spread

Retrotransposons are genetic elements that can actually amplify themselves in the genome by duplicating themselves and then reinsert back into the genome. Sounds pretty wild, and perhaps it is not so surprising that such natural fiddling with your genome could lead to a disease. This is exactly what a team of scientists had shown not long ago, by demonstrating that an increase in LINE-1 retrotransposons was associated with an increased likelihood of autoimmune diseases.

In essence, what this is showing is that viral-like elements within our own genome can trigger our immune system to work against ourselves. It is the increase in the retrotransposons’ productions (based on the DNA blueprint) that leads to the stimulation of interferon manufacture which is involved in the mounting of the immune system against viral pathogens.

Image of Merogenomics article quote on diseases caused by virus

If these retrotransposons can cause harm, why are they found in the human genome? Why have they not been removed by evolutionary pressures? Are these elements perhaps required to fulfill another important biological role? Could they actually be needed for the survival of the species? There are pleeeeeeenty of them in our genomes, repeated over and over! Repetitive DNA sequences comprise more than 50% of the human genome, and a typical human genome contains about 100 active LINE-1 element copies per genome! Other such transposable elements can number in the thousands for active copies, and they truly act in an independent “selfish” manner. They have also been identified in cancer genes, with studies showing four or more somatic retrotransposon insertions per tumor in genes that are commonly mutated in cancer.

Image of Merogenomics article quote on human genome structure

Image of Merogenomics article quote on DNA mutations

If we were to assume that these elements are a requirement, one reason that may come to mind is the evolutionary role. After all, mutagenesis is required for the overall survival of the species, and these repetitive elements are found in practically all types of organisms. In nature, a certain susceptibility to the mutagenesis of the genome is retained as a prerequisite for the adaptation to new environments. In other words, mutations occur to produce enough variability in the genomes of a population to ensure that some fraction of that population could survive in the face of dramatic environmental changes, or the majority of the population in the case of a gradual alteration of the environment. The environment itself provides the selecting pressure, and because it is always changing, each species needs to be able to adapt by changing themselves. This can only be achieved by changes to the genome, as it is the code of life passed onto each generation.

Image of Merogenomics article quote on effects of climate change on species

This raises an interesting, though somewhat obscure, ethical question: if mutagenesis is required for the survival of the species, and diseases that are found in the population arise due to such mutagenic events, then could disease prevalence in the population be a sign of a species’ ability to adapt to a changing world? For the survival of a species, a certain threshold level of mutagenesis is needed. Beyond this threshold, if mutagenesis were to be too frequent, the resulting level of diseases could endanger the species by overwhelming its capacity to successfully thrive and reproduce. If the mutagenesis level is far below such a threshold, then it endangers the survival of the species by leading to species DNA that is not versatile. The lack of such versatility could expose the species to rapid eradication because not enough members would be adapted to a completely new environment in order to ensure its ability to thrive. Think of dinosaurs. Or any currently endangered species that has a very low number of individuals. A simple virus infection could wipe such a species out of existence at this point.

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Of course no one wants diseases, even if their production in the genome is actually needed, as such random mutations also produce variety. The vast majority of these resulting mutations appear to be adapted to the current world, and, more importantly, potentially to future world conditions that for the current majority could be quite adverse. Mutagenesis is evolutionarily built into the world of nature.

Let’s assume this is true, and that we come to an understanding that a certain level of alterations to our genomes, of any kind that is already naturally occurring, is required for species survival. Then should humans ever attempt to alter that mutagenesis rate? This is what I meant by an obscure ethical dilemma! What this could suggest is that diseases should be treated without touching the germline genome, which is the genome of the cells used for reproduction. Why? Because by altering the germline genome (meaning the genome that can be passed on to subsequent generations), even if it is in order to treat diseases, humanity could be inadvertently impacting the favourable mutagenesis conditions which actually ensure that the species possesses the adaptability to changing new environments. In other words, the natural genome as we know it now (as the human genome at this moment is still pure from synthetic manipulation), should remain in its natural state. Apart from causing a very serious mistake of unknown consequences if attempted, it likewise runs the risk of exposing ourselves to the potential destruction of our species by impeding the proper variety of genomes.

Image of Merogenomics article quote on species genome editing

This brings us to another moral quandary: that ethically we should consider if we have the right to deny this privilege to other species, by manipulating their genomes without actually knowing if we are inadvertently affecting their mutation rate as needed for long-term survival. That would be interesting information to know, what this threshold of mutagenesis needed for species adaptability is exactly. Or if it could exist without any diseases actually present? On the other hand, perhaps it does not really matter what mutation rate a species needs to enhance its long-term existence, as in the end it comes down to random events, and the winners are only those who retained the right genomes to exist in a given environment. Whether they had a “favourable” mutagenesis rate or not.

Perhaps all of what I am suggesting is just an exaggeration. After all, if nature already has the means to manipulate our genomes, what difference does it make if we tinker with it on top of that? Could we really threaten the survival of a species by inadvertently altering certain natural processes by altering our genomes?

Yet being vigilant about genome editing is not a slight matter. The previous CIA director John Brennan called genome editing a national security threat. And he was right!

Image of Merogenomics article quote on DNA and national security

Genome editing is advanced enough to produce sophisticated weapons. Think about vaccines that we already have, in that they are sophisticated tools which fool our immune system into recognizing the real infection when it arrives. Or the fact that synthetic species are already being made. That is also without the knowledge of how we might be impacting entire species by the production of novel ones. And, in part because of modern measuring capabilities, we are unravelling a new understanding of how complex environmental interactions can be. They are so complex, that attempts to modify them could have profound and unknown consequences. Look, we are just discovering links between bacterial flora and oral cancer. We have yet to understand the complicated interplay of genomes between bacteria, viruses, and their hosts.

Image of Merogenomics article quote on bacteria and cancer

I suppose this type of thinking could be extended to any part of the natural environment that humans are affecting, and that would be a long list! It looks like we are not well adapted to complex mutual harmony, so the CIA director was right, this can endanger our security. Whenever I hear about the topic of national security on the news, I tend to ignore it because there are so many threats always being mentioned, one just can’t pay attention to all of it. We are bombarded with it (pun not intended)!

But I totally agreed when I heard about this one. Editing genomes is certainly a threat to security. It is a threat to national security, such as a biological weapon attack, which is what the CIA director John Brennan had in mind I think, but also to global security, which is why such pan-continental monitoring organizations exist, like the WHO, to observe how global human health might be affected by epidemics, or the distribution of infectious agents.

We have built smart global networks of great complexity to rapidly respond to any threats and protect ourselves on a global level. The H1N1 response was an example of this that many can remember. More recently, there was an E. bola outbreak as well. But we have not accounted yet for the ever-increasing ability to alter and synthesize new genomes that could be used to create weapons to attack innocent people.

This is my smartest response to the worries that plague the CIA director (seriously, no puns intended!).

First and foremost, rapidly plan an international treaty, in which all the countries of the world agree to never use genome editing to produce bioweapons of any kind. Get that out of the way, and then look for additional solutions. At least in the meantime, the whole world will be keeping an eye on any country trying it. Any country that tries will receive a collective global shaming, which is not unlike what basically happens in the world now anyway (whether reasons are faked or real). That at least buys some time for everyone else to more coolly discuss the subject of why genome editing based weapons should not be produced, and so the message can sink in. Whether to kill people or any species, the simplest argument that comes to my mind is that we could all be inadvertently affected, and perhaps in a rapid fashion. Because we are talking about self-replicating biological systems here.

Why even think about these obscure ethical dilemmas? Because now we could probably be able to measure these rates. What is this mutagenesis rate? How do we know what rate is needed to ensure adaptability versus that which becomes detrimental to humans? I saw a statistic by the National Institute of Health which estimates that 1 in 10 people have a rare disease. Someone else who saw that told me that surely it has got to be nonsense, but now I wonder, is it really? Obviously we do not see the impact of rare diseases often, or so we think: how often can a disease manifest in symptoms which we could assume are normal? Perhaps what looks like normal to us, might be symptoms of a rare disease that does not appear to impact our lives at first glance.

Image of Merogenomics article quote on genetic disorders frequency

One example is undiagnosed mothers with mild symptoms of DiGeorge syndrome, caused by the partial deletion of one of their chromosomes. Even when substantial genomic alteration has occurred such as chromosomal loss, the symptoms can be so mild as not to impact the reproductive fitness of such women. In other instances, such dramatic changes in the chromosomal structure have a very profound effect on phenotype. So perhaps this 1 in 10 people possessing a rare disease is not such a crazy idea! Incidental findings are discovered in the population at a rate of 1-5% based upon the range of studies. Those are variants that are considered to need action or close monitoring. Add to this all of the variants of different diseases of mild phenotypes that we still do not know about, then I can totally see that taking up a few percentage points in the general population. There are also diseases that just might take a very long time to materialize, and will not be experienced till one’s late adult years.

So 1 in 10 doesn’t sound that crazy at all.

Image of Merogenomics article quote on rare diseases symptoms

So let’s assume that diseases are a good representation of the random mutagenesis that is required for genome long-term survival based on the adaptation to a changing environment. Let’s also assume that these “1 in 10” projections of rare diseases are accurate, although that seems like a lot! One in ten people have something potentially impacting their health as a cost of environmental adaptability? The good news is that we are seeing the majority of them as minor impacts. It is like the variants tied to cardiovascular diseases, in that there are just so many, that their interlude is still much of a mystery. Hence, the majority of these variants that are involved are not useful in their predictive power until their role is more precisely understood. It appears that there are so many possible contributions to our cardiovascular system management, that there is plenty of room to make small mistakes in the genome, and the system manages to run long enough until at least babies are produced. But add them all up (variants, not the babies), and it contributes to one of the leading causes of death in the western world. Same with these mild diseases, in that anyone could be carrier of some allele that is negatively impacting their health, and no one would be the wiser. A disease that severely impacts one’s quality of life is luckily a rare event.

1 in 10 individuals to have a disease, even if it is a mild one, so that random mutagenesis events can produce individuals that can always adapt to new future environments. As though there are not enough of these selecting environmental pressures on us! Think of the chemical exposure alone that humans now endure as opposed to in the past - it is worlds apart. Then there is the cancer impact. As for electronic instruments, who knows? We are constantly under natural selection, and natural events appear to be built in to ensure a certain rate of mutation with each generation. It is highly questionable if humans should be altering this ordinary course of events by altering the genetic make-up of organisms capable of reproducing in the wild. And if we are to do so, we better know exactly what we are doing and what results to expect. To sum it up with words of the former CIA director, “even beneficial advances can have destabilizing effects in the long run”, and I couldn’t agree more. Scientific vigilance will be the key in protecting ourselves from the overreaching effects of these novel and exciting technological developments.

There is nothing wrong with being prudent, and ethical discussions should always take place. Including between you, and your family and friends! As this is one topic that I bet you had not considered before, and if it made you think on another level, consider sharing it. While on the topic of diseases, Merogenomics Inc. can help individuals with undiagnosed diseases get access to genomic technologies in a bid to help identify what might be the biological root cause. If you need help, we are here to help.

 

This article has been produced by Merogenomics Inc. and edited by Kerri Bryant. Reproduction and reuse of any portion of this content requires Merogenomics Inc. permission and source acknowledgment. It is your responsibility to obtain additional permissions from the third party owners that might be cited by Merogenomics Inc. Merogenomics Inc. disclaims any responsibility for any use you make of content owned by third parties without their permission.

 

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