In biology, epigenetics is the study of stable phenotypic changes that do not involve alterations in the DNA sequence. The Greek prefix epi- in epigenetics implies features that are "on top of" or "in addition to" the traditional genetic basis for inheritance. Epigenetics most often involves changes that affect the regulation of gene expression, but the term can also be used to describe any heritable phenotypic change. Such effects on cellular and physiological phenotypic traits may result from external or environmental factors, or be part of normal development.
Regulation of gene expression, or gene regulation, includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products. Sophisticated programs of gene expression are widely observed in biology, for example to trigger developmental pathways, respond to environmental stimuli, or adapt to new food sources. Virtually any step of gene expression can be modulated, from transcriptional initiation, to RNA processing, and to the post-translational modification of a protein. Often, one gene regulator controls another, and so on, in a gene regulatory network.
A designer baby is a baby whose genetic makeup has been selected or altered, often to not include a particular gene or to remove genes associated with disease. This process usually involves analysing a wide range of human embryos to identify genes associated with particular diseases and characteristics, and selecting embryos that have the desired genetic makeup; a process known as preimplantation genetic diagnosis. Screening for single genes is commonly practiced, and polygenic screening is offered by a few companies. Other potential methods by which a baby's genetic information can be altered involve directly editing the genome before birth, which is not routinely performed and only one instance of this is known to have occurred as of 2019, where Chinese twins Lulu and Nana were edited as embryos, causing widespread criticism.
Medical genetics is the branch of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from human genetics in that human genetics is a field of scientific research that may or may not apply to medicine, while medical genetics refers to the application of genetics to medical care. For example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counselling people with genetic disorders would be considered part of medical genetics.
Charles David Allis is an American molecular biologist, and is currently the Joy and Jack Fishman Professor and head of the Laboratory of Chromatin Biology and Epigenetics at The Rockefeller University.
Computational epigenetics uses statistical methods and mathematical modelling in epigenetic research. Due to the recent explosion of epigenome datasets, computational methods play an increasing role in all areas of epigenetic research.
Manel Esteller graduated in Medicine from the University of Barcelona in 1992, where he also obtained his doctorate, specializing in the molecular genetics of endometrial carcinoma, in 1996. He was an invited researcher at the School of Biological and Medical Sciences at the University of St Andrews, Scotland, during which time his research interests focused on the molecular genetics of inherited breast cancer.
Sir Adrian Peter Bird, is a British geneticist and Buchanan Professor of Genetics at the University of Edinburgh. Bird has spent much of his academic career in Edinburgh, from receiving his PhD in 1970 to working at the MRC Mammalian Genome Unit and later serving as director of the Wellcome Trust Centre for Cell Biology. His research focuses on understanding DNA methylation and CpG islands, and their role in diseases such as Rett syndrome.
Siddhartha Mukherjee is an Indian-American physician, biologist, and author. He is best known for his 2010 book, The Emperor of All Maladies: A Biography of Cancer, that won notable literary prizes including the 2011 Pulitzer Prize for General Non-Fiction, and Guardian First Book Award, among others. The book was listed in the "All-Time 100 Nonfiction Books" by Time magazine in 2011. His 2016 book The Gene: An Intimate History made it to #1 on The New York Times Best Seller list, and was among The New York Times 100 best books of 2016, and a finalist for the Wellcome Trust Prize and the Royal Society Prize for Science Books.
Genome editing, or genome engineering, or gene editing, is a type of genetic engineering in which DNA is inserted, deleted, modified or replaced in the genome of a living organism. Unlike early genetic engineering techniques that randomly inserts genetic material into a host genome, genome editing targets the insertions to site-specific locations. The basic mechanism involved in genetic manipulations through programmable nucleases is the recognition of target genomic loci and binding of effector DNA-binding domain (DBD), double-strand breaks (DSBs) in target DNA by the restriction endonucleases, and the repair of DSBs through homology-directed recombination (HDR) or non-homologous end joining (NHEJ).
Cancer epigenetics is the study of epigenetic modifications to the DNA of cancer cells that do not involve a change in the nucleotide sequence, but instead involve a change in the way the genetic code is expressed. Epigenetic mechanisms are necessary to maintain normal sequences of tissue specific gene expression and are crucial for normal development. They may be just as important, if not even more important, than genetic mutations in a cell's transformation to cancer. The disturbance of epigenetic processes in cancers, can lead to a loss of expression of genes that occurs about 10 times more frequently by transcription silencing than by mutations. As Vogelstein et al. points out, in a colorectal cancer there are usually about 3 to 6 driver mutations and 33 to 66 hitchhiker or passenger mutations. However, in colon tumors compared to adjacent normal-appearing colonic mucosa, there are about 600 to 800 heavily methylated CpG islands in the promoters of genes in the tumors while these CpG islands are not methylated in the adjacent mucosa. Manipulation of epigenetic alterations holds great promise for cancer prevention, detection, and therapy. In different types of cancer, a variety of epigenetic mechanisms can be perturbed, such as the silencing of tumor suppressor genes and activation of oncogenes by altered CpG island methylation patterns, histone modifications, and dysregulation of DNA binding proteins. There are several medications which have epigenetic impact, that are now used in a number of these diseases.
Paul S. Knoepfler is an American biologist, writer, and blogger. He is a professor in the Department of Cell Biology and Human Anatomy, the Genome Center, and the Comprehensive Cancer Center at the University of California, Davis School of Medicine. In 2013, Knoepfler was named one of the 50 most influential people in the stem cell field.
Epigenome editing or Epigenome engineering is a type of genetic engineering in which the epigenome is modified at specific sites using engineered molecules targeted to those sites. Whereas gene editing involves changing the actual DNA sequence itself, epigenetic editing involves modifying and presenting DNA sequences to proteins and other DNA binding factors that influence DNA function. By "editing” epigenomic features in this manner, researchers can determine the exact biological role of an epigenetic modification at the site in question.
Tapas Kumar Kundu is an Indian molecular biologist, academician and at present the Director of Central Drug Research Institute, a prestigious research institute of Council of Scientific and Industrial Research at Lucknow. He is the head of the Transcription and Disease Laboratory of Jawaharlal Nehru Centre for Advanced Scientific Research. He is known for his studies on the regulation of Gene expression and his contributions in cancer diagnostics and the development of new drug candidates for cancer and AIDS therapeutics. He is an elected fellow of the Indian Academy of Sciences, Indian National Science Academy and the National Academy of Sciences, India and a J. C. Bose National Fellow of the Department of Science and Technology. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, in 2005, for his contributions to biological sciences. He is also a recipient of the National Bioscience Award for Career Development of the Department of Biotechnology.
Human germline engineering is the process by which the genome of an individual is edited in such a way that the change is heritable. This is achieved through genetic alterations within the germ cells, or the reproductive cells, such as the egg and sperm. Human germline engineering is a type of genetic modification that directly manipulates the genome using molecular engineering techniques. Aside from germline engineering, genetic modification can be applied in another way, somatic genetic modification. Somatic gene modification consists of altering somatic cells, which are all cells in the body that are not involved in reproduction. While somatic gene therapy does change the genome of the targeted cells, these cells are not within the germline, so the alterations are not heritable and cannot be passed on to the next generation.
Pharmacoepigenetics is an emerging field that studies the underlying epigenetic marking patterns that lead to variation in an individual's response to medical treatment.
The He Jiankui affair is a scientific and bioethical controversy concerning the use of genome editing following its first use on humans by Chinese scientist He Jiankui, who edited the genomes of human embryos in 2018. He became widely known on 26 November 2018 after he announced that he had created the first human genetically edited babies. He was listed in the Time's 100 most influential people of 2019. The affair led to legal and ethical controversies, resulting in the indictment of He and two of his collaborators, Zhang Renli and Qin Jinzhou. He eventually received widespread condemnation from all over the world.
CRISPR gene editing is a genetic engineering technique in molecular biology by which the genomes of living organisms may be modified. It is based on a simplified version of the bacterial CRISPR-Cas9 antiviral defense system. By delivering the Cas9 nuclease complexed with a synthetic guide RNA (gRNA) into a cell, the cell's genome can be cut at a desired location, allowing existing genes to be removed and/or new ones added in vivo.
A Brief History of Everyone Who Ever Lived: The Stories in Our Genes is a popular science book by British geneticist, author and broadcaster Adam Rutherford. It was first published in 2016 in the United Kingdom by Weidenfeld & Nicolson. An updated edition was published in the United States in 2017, with a different subtitle, by The Experiment. The book is about human genetics and what it reveals about human identity and their history.
