The Epigenetics Revolution: How Modern Biology is Rewriting Our Understanding of Genetics, Disease and Inheritance

The book is masterly in its treatment of this young, exciting, and profoundly significant field of biological research. The author's writing is clear, substantive, vivid, acutely insightful in matters relating to evolution, witty while her frequent use of analogy exemplary. In the course of the book, the author revisits topics in varying contexts but far from this being repetitious on the contrary it refreshes and embeds concepts in the mind of the reader and enhances its interconnection. Another positive element in the book is that on several instances there is a pictorial illustration of the issue raised by the author so that the reader has the benefit to visually follow the sequence of events on the issue raised. I have, however, to warn the prospective reader that the preceding notwithstanding the book is intrinsically not an easy read due to its conceptual richness, the multiplicity, subtlety, intricate sequence of interactions and the complexity of the epigenetic code - especially as related to histone modifications as opposed to DNA methylation - much of it presently understood only in broad outline. Until the turn of the century DNA was viewed as a blueprint or a template but since then there was a paradigm shift and we now correctly view it as a script and as such identical starting points may lead to different outcomes. It is possible without change in DNA (mutation) for life histories to be changed irrevocably in response to the environment through epigenetic changes in our genome. We infer that a phenomenon is likely to be influenced by epigenetic alterations in DNA and its accompanying proteins if one or both of the following are met: two things are genetically identical, but phenotypically variable; an organism continues to be influenced by an event long after the initiating event has occurred. Since all phenotypic variation has a physical basis, we can define epigenetics at the molecular level as the set of modifications to our genetic material that change the ways of gene expression - switch on, switch off, or some intermediate stage - but which does not alter our genome which we can transmit in all its purity to our descendants. The above also solved the mystery that only 2 per cent of our genome codes for proteins while 98 per cent does not code for proteins but as we now realize codes for something else which is connected with regulating gene expression through epigenetic mechanisms. We have similarly come to the realization that the complexity of living organisms scales much better with the percentage that does not code for proteins than it does with the number of base pairs coding for proteins. Further it has been argued that the difference between humans and our chimpanzee relatives may well be due to a special class of ncRNA (non coding RNA) which has an immense capacity of editing itself. Evolution seems to have solved the problem of creating more complex and sophisticated organisms by altering the regulation of the organisms than altering the proteins themselves. And this is exactly what has been achieved by using complicated networks of ncRNAs molecules to influence how, when and to what degree specific proteins are expressed. I shall now reconnect to an earlier part of the review to present epigenetics in action both when two individuals are genetically identical but phenotypically different and when individuals continue to be influenced by an event long after the initiating event has occurred. The scientific term for identical twins is monozygotic (MZ)twins. They were both derived from the same single-cell zygote formed from the fusion of one egg and one sperm. (MZ) twins allow us to explore mathematically the link between the sequences of our genes (genotype) and what we are like (phenotype). In genetically identical monozygotic twins, the concordance for schizophrenia does not reach 100 per cent but is only 50 per cent. The Dutch Hunger Winter lasted from the start of November 1944 to the late spring of 1945. The effects of the famine on the birth weights of children who had been in the womb during that terrible period were: if a mother was well-fed around the time of conception and malnourished only for the last few months few months of the pregnancy, her baby was likely to be small. If, on the other hand, the mother suffered malnutrition for the first three moths of the pregnancy, but then was well fed, she was likely to have a baby with a normal body weight. But then came the really surprising:babies who were born small tended to stay small all their lives - even though they were properly nourished - with lower obesity rates than the general population. Even more unexpectedly, the children whose mothers had been malnourished only early in pregnancy, had higher obesity rates than normal. And the truly stunning, some of these effects seem to be present in the children of this group, that is the grandchildren of women who were malnourished during the first three months of their pregnancy. Something suggesting Lamarckian inheritance and this is indeed what happened and has a name 'transgenerational inheritance'. But I want to reassure the reader because in the overwhelming number of cases, Darwinian evolution prevails. A child, less than three years old, is abused and neglected by his parents but subsequently is treated normally. Often such children who suffered from abuse or neglect in their early years have substantially higher risk as adults of mental health problems than the general population. All too often the child grows up into an adult at high risk of depression, self harm, alcohol and drug abuse, and suicide. We shall now turn our attention to the epigenetic modifications at the molecular level which influence gene and protein expression. The epigenetic regulation of gene expression occurs through different cells having the same DNA blueprint but carrying molecular modifications which can be transmitted from mother cell to daughter cell during somatic cell division. We shall examine in some detail DNA methylation and histone modifications. DNA methylation: Cytosine is the only one of the four DNA bases that gets methylated, to form 5-methylcytosine through one of three enzymes called DNA methyltransferases. The DNMTs are examples of epigenetic 'writers' - enzymes that create the epigenetic code. Most of the time these enzymes will only add a methyl group to a C (Cytosine) that is followed by G (Guanine). C followed by G is known as CpG. The chemical group is 'stuck onto' DNA but does not alter the underlying genetic sequence. DNA methylation has profound effects on how genes are expressed and ultimately on cellular, tissue and whole-body functions. CpG pairs are concentrated in the promoter region. Promoters are the stretches of the genome where transcription complexes bind and start copying DNA to form RNA. Regions where there is a high concentration of CpG motifs are called CpG islands. When genes are active, the levels of methylation in the CpG islands is low. The CpG islands tend to be highly methylated only when the genes are switched off. DNA methylation is clearly really important. Defects in reading DNA methylation can lead to a complex and devastating neurological disorder that leaves children with Rett syndrome severely disabled throughout their lives. DNA methylation is also important for maintaining the correct patterns of gene expression in different cell types, either for several decades in the case of our long-lived neurons or in all daughters of a stem cell in a tissue that is constantly replaced such as skin. Histone modifications: More than fifty different epigenetic histone modifications have been identified. These modifications all alter gene expression but not always in the same way. Some histone modifications push gene expression up, others drive it down. The pattern of modifications is referred to as a histone code and is extraordinarily difficult to read. This complexity contrasts with the fairly all-or-nothing effect of DNA methylation. As to why organisms evoved such complex patterns of histone modifications to regulate gene expression, the author offers an elegant explanation. She argues that complexity likely allows sophisticated fine-tuning of gene expression. Because of this, cells and organisms can adapt their gene expression appropriately in response to changes in their environment. I find it fitting to conclude the review with an apt comment of the author: In biology Darwin and Mendel came to define the 19th century as the era of evolution and genetics; Watson and Crick defined the 20th century as the era of DNA, and the functional understanding of how genetics and evolution interact. But in the 21st century it is the new scientific discipline of epigenetics that is unraveling so much of what we took as dogma and rebuilding it in an infinitely more varied, more complex and even more beautiful fashion.

A good book and really well written. It's a great way for anyone with a basic interest in genetics to start to understand that genetics is so much more than just the basic code of DNA. Fascinating in parts, but I wanted more depth to it and a bit more high level knowledge. But it's aimed at the casual science reader and for that I love it! Brilliant book and should be read by anyone with even a vague interest in genetics.

This is a great book for anyone who like me, is trying to make sense of what is really going on in the genome, in that it brings together many facts from research papers. I've given it five stars for this reason, and despite my many criticisms below, because it tackles an incredibly complex subject in an understandable and fascinating way. The criticisms come from my intense prior involvement in the subject, and are challenges to some of the ideas which I hope might help other readers. The book fails to put over the central story regarding the big question, "what is going on in the genome and to what ends?" I say this because the reader is led to believe that epigenetics explains many things that could not be explained before, such as how cells acquire their individual identity and retain it over decades. Methylation, we are told here, has been said to be virtually irreversible, so it fits the bill, but as we are later told the effects of methylation can be undone by further addition. Notable for their absence are the terms 'transcription factor', and ''genetic cascade' (they are not even in the index), though they are the bedrock of genetic theory; complex books have been written explaining cell fate and development in these terms, and we have no reason to dump the existing theory. A gene can make a protein which is a transcription factor, which can turn off another gene, and there is no reason why that gene cannot go on doing that in a cell and it's copies, through various mechanisms, ad infinitum - no need for methylation to suppress the gene. We should really be asking what methylation adds to the existing processes. It may be 'belt and braces', or it may be, as I think, much more complex than that. Again, later in the book, it is suggested that the permanence of methylation makes it the ideal candidate as the cause of PTSD (post traumatic stress disorder). Only after this idea has been developed in detail is it stated that memory may also be epigenetically determined. Memory, of course, is a far bigger subject than PTSD, and a very complicated one in which the growth of both new connections and new synapses (and possibly glial cells) has long been recognised as a perfectly good explanation of how neurons build and strengthen association. These processes may indeed be under control of epigenetics, but epigenetics isn't necessary for an explanation - again transcription factor cascades, or just the fact that synapses remain once they have been induced to form by neural firing are sufficient. PTSD undoubtedly arises out of memory; and especially emotional memory which appears to get separated from other memories, but memory is a much more complex process than can just be put down to epigenetics. I'm not saying that epigenetics isn't important - I think it's hugely important; just that Carey tends to jump to conclusions in a less than thorough way. There is much mention of 'mental illness' in the book, again with methylation implicated especially in the 'diseases' of PTSD and 'depression'. While the author does a great, and much needed job of explaining how paradigm shifts can take a long time in science because of inertia in the system which resists the overthrow of established ideas, she is clearly unaware of the paradigm shift that has long been underway in the field of so called 'mental illness', especially in the UK, where DSM (the Diagnostic Statistical Manual) has long been viewed with disdain by many psychiatrists, clinical psychogist, and therapists. I suspect that the author's involvement in the pharmaceuticals field has blinded her to this. Many experts, such as Professor Richard Bental ('Doctoring the Minds' and 'Madness Explained') regard depression and even schizophrenia as understandable consequences of pressure from society and family (see also R D Laing's 'Politics of the Family' etc and Bateson's double bind hypothesis). Carey's search for a simple 'cause', though valid to some degree, is much too crude, and ignores so many complex factors. Her quoting of identical twin studies (too often glibly trotted out in general) needs to be questioned. Even twins who grow up together don't share the same experiences - one might have been traumatised, chastised, or otherwise changed in a fleeting moment while the other was absent - this is what creates differing personalities, and it does so through memory, the functioning of the mind, and even psychosomatic effects. All of these are down to neural networks, and we don't understand the functioning of neural networks yet, even at a quite basic level. It's jumping to conclusions to think that epigenetics is suddenly the key to 'mental illness'. An interesting fact about PTSD which caught my attention years ago, is that the commonly prescribed beta-blocker, propranolol, has been found to prevent PTSD if given to soldiers prior to battle. It is also said to 'kill conscience', and there is considerable evidence from research that emotional memories are erased and then put back when we remember events, and that re-living traumatic events while taking propranolol can block that 'putting back'. This poses serious questions for the role of methylation - how is the methylation in neurons involved in emotional memories undone every time we remember something; and if memories are constantly erased and put back, even those causing PTSD, doesn't that rather conflict with the argument that the permanence of methylation is the key? And does propranolol in fact affect methylation or some process around it (a topic for research)? As I said, I'm not the average reader, having been passionately involved in these subjects for thirty or more years, and I know just how mind-bogglingly complicated they are becoming. All the more credit to Nessa Carey for tackling them in a book now, because studying papers is exhausting and takes time, even when you have access to them, and we need books that try to summarise, and access to other's ideas, if what E O Wilson calls 'consilience' across science disciplines is to be achieved. A great book, and I look forward to reading the next one on 'Junk' DNA when it comes out.

Before I read this book my understanding of genetics was quite naive, I thought DNA made proteins, and if there are mutations in the DNA code then that leads to trouble, such as cancer. But only 2% of the human genome makes protein - what is the other 98% for? Also consider this: A caterpillar that becomes a butterfly has exactly the same DNA - so why do they look so different? The answer is 'epigenetics'. Whenever two genetically identical individuals are non-identical in some way we can measure, this is called epigenetics. This also includes an individual at different point in their life. For example why does horrendous abuse as a child often lead to problems later in life - is it psychological or is it embedded in the very genes of the person? In the following sentence, before I read this book, I mostly understood the word 'within'. "Histone Acetylation and DNA methylation within a CpG motif in the promoter region mediates gene expression ...." By half way through this book I understood what this meant. The author never hides the gritty details from the reader unlike many patronising popular science books that shy away from the scientific detail in case the reader finds it too difficult. She takes you step by step through the main details of epigenetics and the technical language used. It is not difficult, but you do have to take it slowly to digest the information. To make the subject a bit lighter, the book is dotted with dry humour and pithy literary quotes. Epigenetics is such a new field that many of the key players are still alive and working away in their laboratories and earning Nobel prizes along the way. She introduces you to some of the leading scientists and the contributions they are making. For example Professor Sir John Gurdon worked for ten years to explain why most cells remain forever of the same type through permanent gene inactivation, it explains why liver cells never become brain cells. Professor Yamanaka is one of the youngest luminaries in the stem cell and pluripotency field. He and his team has managed to convert adult cells back into pluripotent stem cells, thus offsetting the sensitive issue of using embryonic stem cells. The latter half of the book covers the application of epigenetics. It starts with cancer and all its complexities and why we are unlikely to hear "Boffin finds cure for cancer" as there are many, many routes to cancer. Then she moves on to mental illness such as schizophrenia and the role this new science may play along with the possible link between memory and genetics. In one chapter the issue of ageing is discussed and its genetic underpinnings and are we likely to find drugs to help us live longer? Finally, the topic of plant genetics is covered and she explains how a bee, a human and a tulip share very similar molecular mechanisms but they use them in a different way. Throughout the book there are references to source material and these are found in the back of the book if you want to learn more (which I do). Epigenetics is only just getting started and the author refers to conferences that occurred even as late as 2011. This is leading edge science. It is a fascinating book. Yes, it is a technically demanding book. But if you are keen to get a deeper understanding of the future of genetics then I highly recommend it.

The promises of the widely hailed genomic revolution did not materialise.The mapping and sequencing of the human genome failed to set in motion great medical breakthroughs because it could only produce a map of the assembly software.It did't explain how it functioned with only 2% of the genome coding for proteins.The DNA blueprint is certainly a starting point but it isn't a sufficient explanation for the complexity of life.It is a script open to multiple interpretations rather than an unchanging mould. Epigenetics is the new discipline that is revolutionising biology.It has found in Nessa Carey a most engaging and lucid exponent.She writes in a clear non patronising manner using interesting and witty analogies to bring to life a lot of dry biochemical or genetic concepts.Barely a page passes without a new morsel of knowledge is offered with enthusiasm. Epigenetics describes the set of modifications to our genetic material that changes the ways the genes are switched on or off without altering the genome.Epigenetic modification doesn't change the sequence of a gene but it alters how and when the gene is expressed. It explains how two organisms can be genetically identical yet phenotypically variable, examples identical twins divergence,queen bees and worker bees,catterpillar and butterfly. The Epigenome is the missing link between nature and nurture as it reflects environmental differences. Epigenetic modifications are heritable in the short term but do not involve mutation of the DNA . It is the mechanism behind transgenerational Lamarckian inheritance ,for instance poor food availability during crucial gestational development may lead to later pathological consequences visiting two successive generations.Even a father's diet can directly influence the gene expression and health of his offspring.The organism can be affected by an environmental event long after this initiating event has occurred.Research shows that abuse and neglect in childhood can often result in mental illness in adulthood through epigenetic mechanisms modulated by hormonal signalling during critical developmental stages. The diverse applications of this new biological revolution are truly mind boggling whether in cancer research. ageing research, cloning process,sex linked disease or the study of memory.Epigeneticists are likely to be at the forefront of the next batch of Nobel prize candidates. The book is a real tour de force, it is timely and informed by the latest genetic research described in an approchable style for the non expert.Its optimism is contagious though I have my reservations about cancer cure or delaying ageing.The genetic story is just beginning to unfold and there is still a lot more to come.This is a good place to start, it is certainly the best popular book on Genetics I have read since Matt Ridley's" Genome".

Nessa Carey's first foray into popular science is a solid example of how difficult concepts can be presented in an interesting way, without endless analogies and simplifications. The book begins, as is necessary, with a slow-paced introduction to the fundamentals of epigenetics - having done a biology degree there was little new for me here - but in the latter chapters the narrative accelerates and steps away from the well-beaten track of the Dutch Hongerwinter and certain twin studies onto applied epigenetics in areas I had never considered, such as in social honeybee development. I also particularly liked the short vignettes accompanying the introduction of big name scientists in the field, while these were sometimes overly-complimentary it was a nice touch to add some personality to an author. Another point of interest was the gutsy prediction of future Nobel prize winners, which seems almost taboo in academic circles. I was surprised at the depth of coverage Carey writes about, with many named non-coding RNAs and histone modifications. While I liked that she got into the nitty-gritty, it may deter those with only a passing interest in the topic. A particular example was the FLC locus and its role in vernalisation, which I remember detesting during an epigenetics module in my undergraduate degree. Overall: a good read that gains pace and ends with comprehensive explanation of some interesting epigenetics. I'd recommend this book to those with some basic biological knowledge.

The epigenetics revolution is an okay book in terms of requiring general knowledge, but it didn't fulfil what I was after. The beginning is the best part: things that we can alter ourselves for our potential offspring like having good nutrition and avoid famines, but then the book goes into some pretty heavy going detail. I was looking for ways that I can alter my epigenetics for the better, but there's very little of that in here. This is more for someone academically studying epigenetics, with some research that I found to be pointless. For example, why do scientists feel the need to try implanting a female-only created embryo into a mouse then act fascinated by the result of miscarriage? Some things are obvious in nature, yes only men and women together can create new life, so why waste research into these areas? It's a good book if you like reading about mice and plants, but I'm more interested in the human aspect.

D.N.A (Deoxyribonucleic Acid) has very much found it’s way into the vernacular of our language. Most of us – I think? – can very easily form a mental picture of a double helix, recall the letters G C T A from our science lessons, and understand that these “letters” somehow form the building blocks of who we are. Most of us will have a grasp on how hereditary genetic traits work, and some of us might even know a few clever facts, like that Identical Twins have the exact same D.N.A. And yet – Identical (Zygotic) Twins, over their life-cycle, can turn out different in many ways. Why? Our cell life is a lot more complex than just the template of our D.N.A; there are other factors playing on the top of this genetic code, switching certain options “off” and “on”. Welcome to the world Epigenetics. As someone who had heard of this term being banded around in science articles and TV shows, I wanted to learn a little bit more – after all, when I did Biology at School (in the mid 1990’s) this stuff certainly wasn’t mentioned on the public radar. Nessa Carey has written an excellent book helping “numpties” like myself grasp hold of this new and exiting field in biology. It’s not a book that is shy of using biological terminology, and it involved me grappling with imagery that I had never even imagined before; but that’s the exciting thing about science! As well as providing you with the knowledge of why your male tortoiseshell cat will be infertile, this book will give you a greater appreciation of the complexity of life at a cellular level.

I've bought these two books after watching a seminar presented by Nessa Carey, the writer of these two masterpieces. I found this book so intriguing that I spent several sleepless nights on reading this one followed by getting print outs of the reference articles and going through them along with two more text books to get more of this topic. Moved by the piculiarity and the adventure of a largely unexplored field of Epigenetics, now I am preparing to deliver my credit seminar on this subject. Just buy this book and start reading it. I swear, no matter from what academic background you are from, you'll feel the charm of it as the way it has been written is so lucid and from very basic level that it is easily understandable by everyone. All I can say, this is the "must have book" to command over this subject. Still thinking? Go get a copy now!

Este libro es una joya para empezar a entender la Epigenética. El autor además de escribir de una manera interesante , amena y bien documentada, aborda los temas conceptuales y las implicaciones de los descubrimientos recientes de la epigenética en la medicina a largo plazo. Se ha convertido en uno de mis libros favoritos del 2019 y 2020. Muy recomendable. Es un placer leerlo.

There isn’t a long list of footnotes waiting for you at the end. The author properly explains the concepts of each chapter within the chapters themselves, foreshadowing topics of future chapters, and occasionally expanding on specific subtopics mentioned earlier. The book has some fairly extensive references in the back, which is always nice to see. I’m glad she doesn’t rely as much on footnotes as other authors do, it aids tremendously in keeping the flow of reading uninterrupted.

Epigenetikle ilgilenen herkese tavsiye ederim. Orijinal dilinde (ingilizce) bir kitap olması çok güzel. Kargoda hızlı ve üründe sorun yoktu.

Quando leio livros fora da minha formação profissional a experiência tende a ser bastante variável. Algumas vezes, não entendo nada e acho ruim. Outras, não entendo nada e gosto da experiência. Esse livro está perto desse segundo caso. Não entendi tudo, mas o pouco que entendi foi muito interessante, tanto que li o livro em dois dias. Mais do que isso, o livro constrói metáforas que simplificam muito ideias que no jargão científico original são bem mais difíceis de absorver. A clareza na exposição é realmente notável. Recomendo a qualquer um que se interesse por genética.