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It is easy to observe that some people are happier than others. But trying to explain why people differ in their happiness is quite a different story. Is our happiness the result of how well things are going for us or does it simply reflect our personality? Of course, the discussion on the exact roles of nature (gene) versus nurture (experience) is not new at all. When it comes to how we feel, however, most of us may think that our happiness
Announced on January 13th by President Obama in his eighth and final State of the Union Address, the multi-billion dollar project will be led by US Vice President, Joe Biden, who has a vested interest in seeing new cures for cancer. Using genomics to cure cancer is being held on par with JFK’s desire in 1961 to land men on the moon.
2016 is here. The New Year is a time for renewal and resolution. It is also a time for dieting. Peak enrolment and attendance times at gyms occur after sumptuous holiday indulgences in December and again when beach wear is cracked out of cold storage in summer. As the obesity epidemic reaches across the globe we need new solutions. We need better ways to live healthy lifestyles.
Knowledge that we all have DNA and what this means is getting around. The informed public is well aware that our cells run on DNA software called the genome. This software is passed from parent to child, in the long line of evolutionary history that dates back billions of years – in fact, research published this year pushes back the origin of life on Earth another 300 million years.
It is hard to quantify the impact of ‘role-model’ celebrities on the acceptance and uptake of genetic testing and bio-literacy, but it is surely significant. Angelina Jolie is an Oscar-winning actress, Brad Pitt’s other half, mother, humanitarian, and now a “DNA celebrity”. She propelled the topic of familial breast cancer, female prophylactic surgery, and DNA testing to the fore.
Society owes a debt to Henrietta Lacks. Modern life benefits from long-term access to a small sample of her cells that contained incredibly unusual DNA. As Rebecca Skloot reports in her best-selling book, “The Immortal Life of Henrietta Lacks”, the story that unfolded after Lacks died at the age of 31 is one of injustice, tragedy, bravery, innovation and scientific discovery.
Kuwait is changing the playing field. In early July, just days after the June 26th deadly Imam Sadiq mosque bombing claimed by ISIS, Kuwait ruled to instate mandatory DNA-testing for all permanent residents. This is the first use of DNA testing at the national-level for security reasons, specifically as a counter-terrorism measure. An initial $400 million dollars is set aside for collecting the DNA profiles of all 1.3 million citizens and 2.9 million foreign residents
Another ‘Awareness Day’, International Kissing Day, is coming up on July 6. It might not seem obvious but kissing, like most subjects can now be easily linked to the science of DNA. Thus, there could be no more perfect opener for my Double Helix column, given the elegance and beauty of a kiss. To start, there is the obvious biological link between kissing and DNA: propagation of the species. Kissing is not only pleasurable but seems to be a solid way to assess the quality and suitability of a mate.
One of the most fun and exciting sources of information available for free on the Internet are the videos found on the Technology, Entertainment and Design (TED) website. TED is a hub of stories about innovation, achievement and change, each artfully packaged into a short, highly accessible talk by an outstanding speaker. As of April 2015, the TED website boasts 1900+ videos from some of the most imminent individuals in the world. Selected speakers range from Bill Clinton and Al Gore to Bono and other global celebrities to a range of academics experts.
In our study analyzing data from the New England Centenarian Study, we found that for people who live to 90 years old, the chance of their siblings also reaching age 90 is relatively small – about 1.7 times greater than for the average person born around the same time.
On 25th March 2015, 530 years after his death, King Richard III of England will be interred in Leicester Cathedral. This remarkable ceremony is only taking place because of the success of DNA analysis in identifying his skeletal remains. So what sort of genes might a king be expected to have? Or, more prosaically, how do you identify a long dead corpse from its DNA? Several methods were used, and in particular the deduction of the skeleton’s probable hair and eye colour raises some interesting questions about future trends in forensic DNA analysis.
Richard III is one of England’s best known kings, largely due to the famous play of William Shakespeare in which he is portrayed as an evil villain. He only reigned for two years and was killed at the age of 32 at the battle of Bosworth in 1485. According to the historical records he was unceremoniously buried at Greyfriars Friary in Leicester. At some stage knowledge of the exact location of Richard’s burial was lost. But in 2012 excavations under a car park at the probable site of the former friary yielded “skeleton 1″. Suspicion of his royal identity was excited by the fact that the skeleton had a severely bent spine causing the right shoulder to be higher than the left. This well-known deformity of Richard was mentioned in a contemporary source, as well as by Shakespeare. Furthermore, the skeleton was male, the age was about right, it had evidently been killed in battle, and the radiocarbon date was consistent with death in 1485.
This was all very suggestive, but it was the DNA analysis that really proved the case. The work was led by a team at the University of Leicester, with participation by many other UK and European centres. It is important to note that this was not the normal type of forensic DNA identification, which relies on comparing a set of highly variable DNA markers to a database. Such analysis is fine so long as your suspect is in the database, but it is no use for identifying a long dead individual who is not in any database.
By far the best evidence for the identity of Richard III comes from the analysis of his mitochondrial DNA. Mitochondria are bodies found in every cell, responsible for the production of energy. They have their own DNA which is passed down the generations only through the female line. Barring the occasional new mutation, the DNA sequence of mitochondrial DNA should be identical from mother to daughter down a particular female line of descent. Like their sisters, males also carry the mitochondrial DNA of their mothers, but they do not pass it down to their own offspring.
Richard will have shared mitochondrial DNA with his sister, Anne of York. Two complete female lines of descent were traced back to Anne of York, one of 17 generations down to Michael Ibsen, a resident of London, and the other of 19 generations down to Wendy Duldig, formerly of New Zealand. Complete sequencing of their mitochondrial DNA showed a 100% match between skeleton 1 and of Michael Ibsen, and a single base change compared to Wendy Duldig. One change over this period of time is quite likely to be a new mutation. The sequence family (haplogroup) to which the mitochondrial DNA sequence belongs is a fairly rare one, so few other people in England in 1485 would have shared it and in fact the team has systematically ruled out all the other males of the period who might have shared it because of a common female lineage with Richard III. So this match is highly significant and is the best piece of evidence that the “skeleton 1″ is indeed King Richard.
By Bdna. gif: Spiffistan derivative work: Jahobr (Bdna.gif). Public domain via Wikimedia Commons
Also applied was a newer method which is a technique for predicting the hair and eye colour of someone from their DNA. The most important variants affecting hair colour are mutations of a gene called MC1R, which encodes a cell surface receptor for a hormone. Individuals carrying variants of the MC1R gene with reduced function are likely to have red or blond hair rather than the normal dark hair. The pigmentation of the iris of the eye depends significantly on a gene called OCA2, encoding a protein which transports tyrosine into cells. Again variants of reduced function give less pigmented eyes, meaning that the colour is blueish rather than brownish. Recently a Dutch group created a forensic test based on variants at 24 genetic loci, of which 11 are in the MC2R gene and the rest in 12 other positions including the OCA2 gene. Identification of these 24 variants yields a fairly accurate prediction of hair and eye colour, and in the case of skeleton 1 the prediction was for blue eyes and blond hair. The existing portraits of Richard III all date from some time after his death but the older ones do indeed show light-coloured eyes and reddish-brown hair, an appearance which is consistent with the prediction.
These two types of analysis indicate two rather different senses in which we use the word “gene”. The sequence variants of the mitochondrial DNA, like those used in normal forensic identification, do not, in general, affect the characteristics of the individuals carrying them. The DNA changes often lie outside actual genes, in the regions of DNA between genes. They are better described as “markers” than as “genes”. But the hair and eye colour analysis is based at least partly on actual gene variants that might be expected to generate those visible characteristics.
How much further might this kind of analysis be pushed? Could the height, facial features or skin colour of a crime suspect be deduced from their DNA? The essential issue is the number of gene variants in the population that affect a feature. If it is relatively small, as with hair and eye colour, then prediction is possible. If it is very large, as for height, then it is not possible, because most of the variants affecting height have too small effects to be detectable. Most of the human characteristics that have been studied in this way have turned out to depend on a very large number of variants of small effect. So, contrary to popular perception, there are real limits to what is possible in terms of prediction of bodily features from DNA data. There will doubtless be some other features that are predictable, and these may eventually include skin colour. But unless a completely new approach is invented, it is unlikely that we shall ever see an identikit picture of a suspect generated from DNA at the crime scene.
Featured image credit: Stained glass, by VeteranMP. CC-BY-SA 3.0 via Wikimedia Commons
Watching the field of genomics evolve over the past 20 years, it is intriguing to notice the word ‘genome’ cozying up to the word ‘million’. Genomics is moving beyond 1k, 10k and 100k genome projects. A new courtship is blossoming.
The Obama Administration has just announced a Million Genomes Project – and it’s not even the first.
Now both Craig Venter and Francis Collins, leads of the private and public versions of the Human Genome Project, are working on their million-omes.
The company 23andMe might be the first ‘million-ome-aire’. By 2014, the company founded by Ann Wojcicki processed upwards of 800,000 customer samples. Pundit Eric Topol suggests in his article “Who Owns Your DNA” that without the skirmish with the FDA, 23andMe would already have millions.
In 2011, China’s BGI, the world’s largest genomics research company, boldly announced a million human genomes project. Building on projects like the panda genome and the 3000 Rice Genomes project, the BGI is building new next-generation sequencing technologies to support its flagship project.
Also in 2011, the United States Veterans Affairs (VA) Research and Development program launched its Million Veteran Program (MVP) aiming to build the world’s largest database of genetic, military exposure, lifestyle, and health information. The “large, diverse, and altruistic patient population” of the VA puts it ahead of the others in collecting samples.
Venter’s path will be through his non-profit Human Longevity, Inc (HLI), launched in San Diego, California in 2014 with $70 million in investor funding. To support the company’s tagline — “It’s not just a long life we’re striving for, but one which is worth living” — Venter aims to sequence a million genomes by 2020.
At a price tag of $1000 dollars per genome, one million genomes could cost a billion US dollars. The original human genome project cost $3 billion only 13 years ago, but produced 1 trillion US dollars in economic impact.
The Collins’ ‘million-ome’ will pull together new and existing genomes, with an initial budget of $215 million dollars. This includes genomes from the MVP, which has already enrolled 300,000 veterans and sequenced 200,000. The focus will initially be on cancer but subjects will be healthy and ill, men and women, old and young; it is the foundation of a Precision Medicine Initiative.
In addition to these projects we will have millions anyway. ARC Investment Analysis suggested we could see 4 to 34 billion human genomes by 2024 at historical rates of sequencing – if current trends in dropping costs and demand continue.
How could we have more genomes than humans living on earth? Cancer genomics is in ‘gold rush’ phase. Steve Jobs was famously one of the first 20 people to have his genome sequenced. He paid $100k but did so to also have the genome of the cancer that killed him sequenced. He left a personal genomics legacy to the world, but his investment in DNA sequencing also serves as a reminder that a genome is not the same as a cure. Hopes are high, though, especially for cancer diagnostics. The International Cancer Genomics Consortium is already backed with a billion dollar budget and the field continues to explode.
Further, an adult human body consists of 37 trillion genomes all working together (plus the 100 trillion genomes of the microbial cells in our microbiome). There is mounting evidence we are all genomic mosaics, meaning we all have more than one genome (e.g. from pre-cancerous cells, transplants, and mothers who carry the genomes of past live-born babies).
It is good to cultivate a healthy skepticism and not be drawn into the hype. Critics exist, as always. At the other end of the continuum, Ken Weiss of The Mermaid’s Tale blog, a geneticist himself, has outlined reasons to put valuable research dollars elsewhere than a million genomes project or precision medicine, but given than they will happen, he also contemplates what should be done with resulting data.
Eric Topol said in response to the rise of ‘million-ome’ projects, that there are now many 100k projects and he “might rather have 100,000 people with ‘pan-oromic definition’ than 1 million with just native DNA”. By high definition he means all the mapping (sensors, anatomy, environmental quantified, gut microbiome, etc.) that belongs to his vision of a “Google medical map”.
There are huge differences between “projections,” “announcements,” and “hard (published) data.” Big projects can fall by the way-side. 23andMe hit a barrier with the FDA decision. The BGI is still tooling up. Obama hasn’t yet secured a budget. Venter is giving himself time. Everyone is starting to think about genomes inside the systems in which they exist in (cells, organs, organisms, ecosystems).
Regardless of trajectory, it is a foregone conclusion that, counting all sources, the number of sequenced genomes will pass one million in 2015, if it hasn’t already.
Google is imagining the day when researchers compute over millions of genomes and is building the infrastructure to support it; Google Genomics has launched offering $25/year pricing to hold your genome in the Cloud.
Why stop at millions? Jong Bhak is calling for billions. He is suggesting that “the genomics era hasn’t even started.” Bhak, a leader of the Korean Personal Genomes Project, a project to sequence the genomes of all 50 million Koreans, has outlined a vision for a Billion Genome Project.
The first to talk of ‘a genome for everyone’ was perhaps George Church, technologist and founder of the Personal Genome Project. He wrote 2005 a paper entitled “The Personal Genome Project.” In it he recalled talking with Wally Gilbert that “Six billion base pairs for six billion people had a nice ring to it”—back in 1976, soon after Gilbert invented DNA sequencing, for which he won a Nobel Prize.
The fact that more voices in global science are debating the pros and cons of ‘millions and billions of genomes’ is evidence that 2015 marks a shift towards a Practical Genomics Revolution. It is becoming practical to think big(ger).
This is the latest post in our regular OUPblog column SciWhys. Every month OUP editor and author Jonathan Crowe will be answering your science questions. Got a burning question about science that you’d like answered? Just email it to us, and Jonathan will answer what he can. Today: what is gene mutation?
By Jonathan Crowe
In my last three posts I’ve introduced you to the world of biological information, taking you from the storage of biological information in libraries called genomes, which house information in individual books called chromosomes (themselves divided into chapters called genes), to the way the cell makes use of that stored information to manufacture the molecular machines called proteins.
But what happens when the storage of information goes wrong? If we’re reading a recipe and that recipe contains a mistake, chances are that the end-result of our culinary endeavour won’t end up as it should. And so it is at the level of cells. If the information the cell is using is somehow wrong, the end result will also be wrong – sometimes with catastrophic results.
I’ve mentioned in previous posts how biological information is captured by the sequence of the building block ‘letters’ from which DNA is constructed. The sequence of letters is ultimately deciphered by a molecular machine called the ribosome, which reads the sequence of letters in sets of three, and uses each trio to determine which amino acid – the building block of proteins – should be used next in its mission to construct a particular protein. It should come as no surprise that, if the recipe for the protein is changed – if the sequence of DNA ‘letters’ is altered – the protein that is manufactured will probably contain errors as a result. And if a protein contains errors, it won’t be able to function correctly, just as flat-packed furniture will end up being decidedly wobbly if you construct it from the wrong parts.
Imagine a snippet of DNA has the sequence GGTGCTAAG. The ribosome would ‘read’ this sequence, and would use it as the recipe for building a chain of three amino acids: Glycine-Alanine-Lysine. Now imagine that we alter just one letter in our original sequence so that it becomes GGTCCTAAG. All we’ve done is swap a G for a C at the fourth position in the DNA sequence. However, this change is sufficient to affect the composition of the protein that is produced when the sequence is deciphered: the ribosome will now build a chain with the composition Glycine-Proline-Lysine.
Surely such a small change won’t actually cause significant problems in a cell, though. Right? Wrong. Amazingly (and perhaps unnervingly) the tiniest error can have really quite significant consequences.
Let’s take just one example. Sickle cell anaemia is a condition that affects the red blood cells of humans. Red blood cells fulfil the essential role of transporting oxygen from our lungs to all the living cells of our body: they continually circulate through our arteries and veins, shuttling oxygen from one place to another. A healthy red blood cell looks a bit like a ring doughnut (though it doesn’t actually have a hole right through the middle); by contrast, the red blood cells of individuals with sickle cell anaemia become warped into crescent-like shapes (like a sickle, the grass-cutting tool, after which the disease is named). These sickle cells no longer pass freely through our arteries and veins. Instead, they tend to get entangled with each other. As a result, the flow of oxygen round the body is impeded, and
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This is the third post in our latest regular OUPblog column: SciWhys. Every month OUP editor and author Jonathan Crowe will be answering your science questions. Got a burning question about science that you’d like answered? Just email it to us, and Jonathan will answer what he can. Today: How is the information in a gene used by a cell?
By Jonathan Crowe
In my last twoposts I’ve introduced the notion that DNA acts as a store of biological information; this information is stored in a series of chromosomes, each of which are divided into a number of genes. Each gene in turn contains one ‘snippet’ of biological information. But how are these genes actually used? How is the information stored in these genes actually extracted to do something useful (if ‘useful’ isn’t too flippant a term for something that the very continuation of life depends upon).
Many (but not all) genes act as recipes for a family of biological molecules called proteins: they literally tell the cell what the ingredients for a particular protein are, and how they should be combined to create the protein itself. (Proteins have a range of essential roles in the human body. Some act as building materials for different components of the body, such as the keratin we find in our hair and nails. Others act as molecular transporters: haemoglobin, which is found in our red blood cells, carries oxygen from our lungs to other parts of the body. A family of proteins called the enzymes are arguably the most important, however. Enzymes cajole different chemicals in our body into reacting with one another. Without enzymes, our bodies would be unable to generate energy from the food we eat (and you’d not be reading this blog post).)
So, somehow, the information stored in a DNA molecule is deciphered by the cell and used as the recipe for a protein. But how?
To answer this question, let’s take a journey inside the cell. We can imagine a cell to be like a factory, but one that has been divided into a series of physically separated compartments. Unlike a factory filled with air, a cell is filled with a jelly-like fluid called the cytoplasm, which surrounds the various compartments enclosed within it. In an earlier post I likened a genome to a biological library. And, inside the cell, this library is stored within a particular compartment called the nucleus.
I mentioned earlier that genes often act as recipes for proteins. But here comes a bit of a quandary: chromosomes – and the genes they contain – are locked away inside the cell’s nucleus. By contrast, proteins are manufactured by the cell in the cytoplasm, outside of the nucleus. So, for the genetic information to be used, it has to get out of nucleus and into the cytoplasm. How does this happen? Well, if we’re in a library with a book that contains information we really need, but we’re unable to take the book out of the library, we might make a photocopy of the page that holds the information we’re after. To get the information it needs out of the nucleus and into the cytoplasm the cell does something remarkably similar. The chromosome containing the gene of interest has to stay inside the nucleus, so the cell makes a copy of the gene – and that copy is then transported to where it is to be used: out of the nucleus and into the cytoplasm.
The copy of the gene generated during this cellular photocopying is made not of DNA but of a close cousin called RNA. RNA is made of three of the same building blocks as DNA – A, C and G. Instead of the T found in DNA, however, RNA uses a different block represented by the letter U (for ‘uracil’). Despite this
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This is the second post in our latest regular OUPblog column: SciWhys. Every month OUP editor and author Jonathan Crowe will be answering your science questions. Got a burning question about science that you’d like answered? Just email it to us, and Jonathan will answer what he can. Today: What are genes and genomes?
By Jonathan Crowe
I described in my last blog post how DNA acts as a store of biological information – information that serves as a set of instructions that direct our growth and function. Indeed, we could consider DNA to be the biological equivalent of a library – another repository of information with which we’re all probably much more familiar. The information we find in a library isn’t present in one huge tome, however. Rather, it is divided into discrete packages of information – namely books. And so it is with DNA: the biological information it stores isn’t captured in a single, huge molecule, but is divided into separate entities called chromosomes – the biological equivalent of individual books in a library.
I commented previously that DNA is composed of a long chain of four building blocks, A, C, G, and T. Rather than existing as an extended chain (like a stretched out length of rope), the DNA in a chromosome is tightly packaged. In fact, if stretched out (like our piece of rope), the DNA in a single chromosome would be around 2-8 cm long. Yet a typical chromosome is just 0.00002–0.002 cm long: that’s between 1000 and 100,000 times shorter than the unpackaged DNA would be. This packaging is quite the feat of space-saving efficiency.
Let’s return to our imaginary library of books. The information in a book isn’t presented as one long uninterrupted sequence of words. Rather, the information is divided into chapters. When we want to find out something from a book – to extract some specific information from it – we don’t read the whole thing cover-to-cover. Instead, we may just read a single chapter. In a fortuitous extension of our analogy, the same is true of information retrieval from chromosomes. The information captured in a single chromosome is stored in discrete ‘chunks’ (just as a book is divided into chapters), and these chunks can be read separately from one another. These ‘chunks’ – these discrete units of information – are what we call ‘genes’. In essence, one gene contains one snippet of biological information.
I’ve just likened chromosomes to books in a library. But is there a biological equivalent of the library itself? Well, yes, there is. Virtually every cell in the human body (with specific exceptions) contains 46 chromosomes – 23 from each of its parents. All of the genes found in this ‘library’ of chromosomes are collectively termed the ‘genome’. Put another way, a genome is a collection of all the genes found in a particular organism.
Different organisms have different-sized genomes. For example, the human genome comprises around 20,000-25,000 genes; the mouse genome, with 40 chromosomes, comprises a similar number of individual genes. However, the bacterium H. influenzae has just a single chromosome, containing around 1700 genes.
It is not just the number of genes (and chromosomes) in the genome that varies between organisms: the long stretches of DNA making up the genomes of different organisms have different sequences (and so store different information). These differences make sense, particularly if we imagine the genome of an organism to represent the ‘recipe’ for that organism: a human is quite a different organism from a mouse, so we would expect the instructions that direct the growth and function of the two organisms to differ.
B
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Dan Agin is Emeritus Associate Professor of Molecular Genetics and Cell Biology at the University of Chicago. His new book, More Than Genes: What Science Can Tell Us About Toxic Chemicals, Development, and the Risk to Our Children, Agin marshals new scientific evidence to argue that the fetal environment can be just as crucial as genetic hard-wiring or even later environment in determining our intelligence and behavior. In the excerpt below, Agin illustrates his premise.
During the next few decades, Americans and others in the industrialized world will learn that the psychological destinies of their children are often shaped and mangled by man-made environmental effects that begin not with birth but with conception. This is an idea that has been quietly gaining momentum in science for some years now, occasionally leaking into the popular press. As it becomes increasingly established, it will challenge the very fundamentals that govern the way we see ourselves and our society.
How will we deal with these effects? Are they real or mere speculation? When and how do they happen?
The origins are beyond what most people imagine.
On the morning of September 11, 2001, some 3000 people died in front of our eyes in a crazy scene of airliners crashing into skyscrapers and of those skyscrapers crumbling within minutes. Anyone downtown in Manhattan that day, or anyone anywhere in front of a television screen who watched the collapse of the twin towers of the World Trade Center, has the memory of it seared into the psyche. The entire appalling event – from Manhattan to the Pentagon to a small field in Shanksville, Pennsylvania – sent political shockwaves across America and around the world that have not yet subsided. We now call that day “9/11″ as a signature shorthand for the catastrophe, a logo for an event whose details quickly occupied the mind of nearly everyone on the planet.
But like many catastrophic events, there was more to 9/11 than most people realize.
Not long afterward, a few miles north of “Ground Zero” – the empty ground where the World Trade Center once stood – a pediatrics group at the Mt. Sinai School of Medicine, together with others there and at the Bronx Veterans Affairs Medical Center, began to ask a simple question: Was it possible the shock of the 9/11 catastrophe had caused effects in the fetuses of pregnant women who lived close to the disaster?
The Mt. Sinai research team went on a hunt for pregnant women who had been in the vicinity of the World Trade Center at 9 a.m. on the 11th of September 2001. They published advertisements in local newspapers. They distributed flyers in lower Manhattan. They sent letters to 3000 obstetricians in the greater New York City area. They found 187 women who had been pregnant and present in any one of five exposure zones around Ground Zero, including 12 women who were in the towers at the time of the attack. As a comparison group, they used 174 pregnant women who had been nowhere near the World Trade Center on the morning of the catastrophe.
The researchers analyzed every piece of relevant information available about the pregnant women in both groups and about the infants born to them in subsequent weeks or months. On August 6, 2003, they published a short letter in a medical journal. The concluding paragraph of the letter had no ambiguities
We found an apparent association between maternal exposure to the World Trade Center disaster and intra-uterine growth retardation, suggestion that this event had a detrimental impact on exposed pregnancies…Possible long-term effects on infant development are unclear and will require continuing follow-up.
Two years later, the Mt. Sinai research group published three papers on their findings in three different medical journals. To sum up their conclusions: The cause of intrauterine growth retardation in the infants was apparently not dust and smoke inhaled by the pregnant mothers, but maternal psychological stress and cortisol secretion effects, as indicated by measures of below-normal cortisol levels in their infants.
The findings of the Mt. Sinai research group are not isolated. Since the late 1990s, fetal effects have been found from earthquakes, ice storms, and floods, with varying later outcomes for the children: childhood verbal deficits, depression, schizophrenia, and so on.
Do we know the mechanism for these effects? There’s more than one possibility, but consider the following: On 9/11, when a pregnant woman was close enough to experience the traumatic World Trade Center event, her adrenal glands secreted the powerful stress hormone cortisol. Her cortisol entered the placenta. Not all of her cortisol was broken down by the placenta, and some of it got through to the fetus and increased the fetal blood cortisol level. Recent studies in fact show a positive correlation between maternal and amniotic fluid cortisol levels. On 9/11, to compensate for increased local cortisol, the fetal adrenals reduced their own cortisol secretion to keep the total level down. But since that happened while the fetus itself was developing, the result was fetal production of cortisol that might not have been just transiently reduced, but permanently reduced. One effect could be retarded intrauterine growth. Another effect would be low cortisol levels in infancy (as found by the Mt. Sinai group) and later consequences difficult to assess. In other words, during development the fetus adapted a new environmental condition as if that condition would be permanent.
In modern pediatrics and developmental psychobiology, this adaptation is called “fetal programming” or “prenatal programming.” It’s a new concept. The general idea is that during development important physiological parameters can be reset by environmental events – and the resetting can endure into adulthood and even affect the following generation – in this case, producing a transgenerational nongenetic stress disorder.
So what are the consequences? Researchers have already correlated heart disease and diabetes with prenatal growth and apparent fetal programming. But “intra-uterine growth” is only what you can see and determine by measuring an infant’s head circumference and body length at the time of birth. What you can’t see are the subtle effects on various physiological systems, for example, on the developing central nervous system – on the developing brain. You can measure behavior later on, but it’s not that easy.
What is certainly true is that you don’t need great drama – earthquakes or flood or terrorism – to affect the prenatal environment. Far subtler events can have an impact on that environment as well.
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University of Chicago. His new book,