Glossary | The Genomic Power Shift

Genomics comes with a lot of words that sound more complicated than they need to be. This glossary gives plain-English definitions of the most important terms, so you can follow the book without needing a degree in genetics, medicine or molecular biology.

Think of it as your quick guide to DNA, genome sequencing, genetic testing, precision medicine, rare disease, cancer genomics, ancestry, biodiversity and the new technologies changing how we understand life.

You do not need to memorise all of this. Understanding enough to see that the genomic era is already here matters far more than being able to drop “polygenic risk score” into dinner conversation.

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Amniocentesis: A prenatal test where a small amount of amniotic fluid is taken from the womb and analysed. It can be used to look for certain genetic or chromosomal conditions in a fetus. Because it is an invasive test, it carries a small risk of miscarriage.
Ancient DNA / aDNA: DNA recovered from old biological material such as bones, teeth, hair, preserved tissue, archaeological remains or museum specimens. Ancient DNA can help identify historical people, reconstruct migrations, study extinct species and show how humans once mixed with other human groups such as Neanderthals and Denisovans.

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Base editing: A newer form of genome editing that can change individual DNA bases without cutting both strands of the DNA double helix. It is sometimes described as a more precise “letter change” tool, although delivery, safety and unintended effects still matter enormously.
Biobank: A collection of biological samples, such as blood, saliva, tissue or DNA, often linked to health, lifestyle or demographic information. Biobanks can be extremely valuable for research and medicine, but they raise difficult questions about consent, privacy, ownership, commercial use and family data.
Biomanufacturing: The use of living cells, enzymes or biological systems to make useful products. Biomanufacturing can involve engineered microbes, cultured cells or synthetic biology to produce medicines, food ingredients, enzymes, materials, fragrances, fuels or chemicals.
Biosafety: The practical measures used to prevent accidental exposure to, or release of, biological materials in laboratories, clinics and industrial settings. Biosafety is about preventing accidents; biosecurity is more about preventing misuse.
Biosecurity: The practices, rules and systems designed to prevent dangerous biological materials, tools or knowledge from being misused. In genomics, biosecurity becomes especially important when gene editing, DNA synthesis, AI and synthetic biology make it easier to design or alter living systems.

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Cell senescence: A state where a cell stops dividing. Senescent cells are not dead, but they no longer renew themselves in the normal way. Cell senescence is linked to ageing, tissue damage, cancer protection and inflammation.
Cellular reprogramming: Techniques that push cells from one biological state into another. Dolly helped show that adult cell identity was not as fixed as scientists once thought; later stem-cell technologies took that idea in new directions.
Chorionic villus sampling: A prenatal test where a small sample is taken from the placenta. It can be used to test for certain genetic or chromosomal conditions before birth. Like amniocentesis, it is invasive and carries a small risk of miscarriage.
Chromosome: A long package of DNA and proteins found inside cells. Humans usually have 46 chromosomes in most cells: 23 from the mother and 23 from the father. Chromosomes carry many of our genes.
CRISPR-Cas9: A genome-editing system adapted from a bacterial defence mechanism. CRISPR-Cas9 can be programmed to cut DNA at specific locations, allowing scientists to disrupt, remove, repair or rewrite genetic sequences, although real biology is usually messier than the clean “molecular scissors” metaphor suggests.

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De-extinction: The attempt to bring back traits, genomes or living proxies of extinct species using tools such as ancient DNA, cloning, genome editing and selective breeding. De-extinction raises scientific and ethical questions about animal welfare, ecosystems, conservation priorities and whether humans should try to reverse extinctions they helped cause.
DNA: DNA, or deoxyribonucleic acid, is the molecule that carries genetic information in living organisms. It is often described as the code of life because it contains instructions that cells use to build and run the body.
DNA barcoding: A method for identifying species using short, standardised DNA sequences. DNA barcoding can help identify fish, timber, insects, plants, fungi, wildlife products and mystery biological samples that are difficult to recognise by appearance alone.
DNA data storage: The use of DNA molecules to store digital information. DNA can theoretically store huge amounts of data in a very small space for a long time, but practical DNA data storage still faces challenges around cost, speed, error correction and retrieval.
DNA phenotyping: The use of DNA to estimate visible or biological traits, such as eye colour, hair colour, skin pigmentation, ancestry or some aspects of age. In forensic contexts, DNA phenotyping can be powerful but ethically sensitive, because it moves DNA analysis beyond matching a known person and toward inferring what an unknown person may look like.
DNA sequencing: The process of reading the order of the chemical letters in DNA. These letters are called bases: A, C, G and T. Sequencing allows scientists and doctors to look for genetic variants, study organisms, diagnose disease and compare genomes.
Dual use: A term for research, tools or knowledge that can be used for beneficial purposes but could also be misused. Many genomic technologies are dual use: the same methods that can help treat disease, track outbreaks or engineer useful microbes could also be used carelessly or maliciously.

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Environmental DNA / eDNA: DNA collected from the environment rather than directly from an organism. Water, soil, air, mud or sediment can contain traces of DNA shed by plants, animals, fungi, microbes and parasites, making eDNA useful for monitoring biodiversity, detecting invasive species and investigating environmental change.
Epigenome: A layer of chemical marks on DNA and its packaging proteins that can influence how genes are switched on or off. It can change how genes behave without changing the DNA sequence itself.

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Forensic genetic genealogy: The use of DNA from a crime scene or unidentified remains to search genetic-genealogy databases and build family trees that may lead to a person’s identity. It can help solve serious crimes and identify the dead, but it also raises privacy questions for relatives who never chose to be part of an investigation.
Free radicals: Unstable molecules that can react with parts of a cell, including DNA, proteins and cell membranes. In small amounts, they are part of normal biology. In excess, they can contribute to cellular damage.

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Gene drive: A genetic system that increases the chance that a particular genetic change will be inherited by offspring. Gene drives could potentially spread traits through wild populations, such as mosquitoes, but they raise major ecological and governance questions because the effects may move beyond the original release site.
Gene editing / genome editing: The deliberate alteration of DNA in a cell or organism. Gene editing can be used in research, medicine, agriculture, conservation and industrial biology, but the ethical questions depend heavily on what is being edited, why, who benefits and whether the change can be inherited.
Gene pool: The total collection of genetic variation in a population. It includes all the different versions of genes found in that group at a particular time.
Gene therapy: A treatment approach that aims to treat or prevent disease by changing, replacing, silencing or adding genetic material in a patient’s cells. Some gene therapies work by delivering genetic instructions directly, while others involve modifying cells outside the body and returning them to the patient.
Genetic carrier testing: A genetic test used to find out whether someone carries a gene variant that could cause disease in their children. This is especially important for recessive conditions, where a person can be healthy but still pass on a disease-causing variant.
Genetic condition: A disease or trait caused partly or entirely by changes in DNA. Some genetic conditions are caused by a variant in a single gene. Others involve many genes plus environmental factors.
Genetic genealogy: The use of DNA testing together with family-tree research to infer biological relationships and ancestry. Genetic genealogy can reconnect families and identify unknown relatives, but it can also uncover adoption, donor conception, misattributed parentage or other family secrets.
Genome: The complete set of genetic material in an organism. In humans, this includes all the DNA in our chromosomes, plus a small amount of DNA in mitochondria.
Genome-driven precision medicine: The use of genomic information to help guide healthcare. It can help doctors choose treatments, understand disease risk, diagnose rare conditions or match patients to therapies based on the biology of their disease.
Genome-wide association study: A genome-wide association study, often shortened to GWAS, looks across the genomes of many people to find genetic variants associated with a trait or disease. GWAS studies are often used for complex conditions where many genetic factors each make a small contribution.
Genomics: The study of whole genomes. Instead of looking at one gene at a time, genomics looks at the full set of genetic information and how genes interact with each other, with the environment and with disease.
Germline editing: Genome editing that affects eggs, sperm, embryos or the cells that give rise to them, meaning the change could be inherited by future generations. Germline editing is ethically different from editing cells in an existing patient because it can alter the genetic inheritance of people who cannot consent.
Germline variant: A genetic variant that is present in the egg or sperm and therefore inherited from a parent. Germline variants are usually present in nearly every cell of the body and can be passed on to children, which is why they often have implications for relatives.

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Human genetics: The study of how genes and genetic variation affect human traits, health, disease and inheritance. It includes everything from rare inherited diseases to ancestry, cancer risk and complex conditions.

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Induced pluripotent stem cell / iPSC: A cell made by reprogramming an adult cell, such as a skin or blood cell, so that it behaves more like an embryonic stem cell. iPSCs can be guided into becoming other cell types, such as heart, nerve or liver-like cells, making them useful for disease modelling, drug testing and future regenerative medicine.

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Karyotyping: A way of looking at a person's chromosomes under a microscope. It can detect large chromosomal changes, such as an extra chromosome 21 in Down syndrome.

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Long-read sequencing: A DNA sequencing method that reads long stretches of DNA at once. This can make it easier to detect structural changes, repeated regions and complicated parts of the genome that are harder to study with short-read sequencing.

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Metagenomics: The study of genetic material taken directly from an environment, such as soil, seawater, the gut or a hospital surface. It allows scientists to study whole communities of microbes without needing to grow them in a lab. A metagenomic analysis does not ask “what organism is this?” so much as “who is here?” It is the difference between identifying one dinner guest and opening the door to find your breakfast, your gut bacteria and your compost bin have all brought friends.
Microarray: A genetic testing method that can detect gains, losses or changes in DNA across the genome. It is often used to find smaller chromosomal changes, such as microdeletions and microduplications, that may not be visible with standard karyotyping.
Monogenic disease: A disease caused mainly by a change in a single gene. Examples include cystic fibrosis, sickle cell disease and Huntington's disease. These conditions often follow clearer inheritance patterns than complex diseases.
Multifactorial disease: A disease caused by a mixture of genetic and environmental factors. Many common conditions, such as diabetes, heart disease, depression and asthma, are multifactorial. There is usually no single gene that explains everything.

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NIPT: NIPT stands for non-invasive prenatal testing. It is a blood test taken from the pregnant mother that analyses small fragments of fetal DNA. It can screen for certain chromosomal conditions without needing an invasive procedure.

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Organoid: A small three-dimensional structure grown from cells that mimics some features of an organ or tissue. Organoids are not miniature fully working organs, but they can help scientists study development, disease, drug response and patient-specific biology in living human tissue models.
Oxidative stress: Oxidative stress happens when the body produces more reactive molecules, such as free radicals, than it can safely neutralise. It can damage cells and has been linked to ageing, inflammation and several diseases.

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Pharmacogenomics: The study of how genetic differences affect a person’s response to medicines. Pharmacogenomics can help explain why a drug works well for one person, does nothing for another or causes serious side effects in someone else.
Polygenic risk score: A polygenic risk score, or PRS, estimates genetic risk by adding up the small effects of many genetic variants across the genome. It does not predict the future with certainty—it gives a probability, and its usefulness depends heavily on the disease, the data and the population it was developed from.
Population: In genetics, a population is a group of individuals of the same species that live in a particular area or share ancestry and can reproduce with one another. Population genetics studies how genetic variation changes within and between such groups.
Precision fermentation: The use of engineered microbes to produce specific molecules, such as proteins, fats, enzymes, flavours, vitamins or food ingredients. It is one way biology is being turned into a manufacturing system, especially in food technology and industrial biotechnology.
Predictive genetic testing: Genetic testing used to estimate a person's risk of developing a disease before symptoms appear. It is often used for conditions where genes increase risk but do not always guarantee disease.
Prenatal genetic testing: Genetic testing carried out before birth, either on a fetus or embryo. It can include screening tests, such as NIPT, or diagnostic tests, such as amniocentesis or chorionic villus sampling.
Presymptomatic genetic testing: Genetic testing used when a person has no symptoms yet, but may carry a gene variant that is strongly linked to a disease that develops later. Huntington's disease is a classic example.
Prime editing: A newer genome-editing method designed to make more precise changes to DNA without always requiring a double-strand break. It is sometimes described as a “search and replace” tool for DNA, although like all genome-editing technologies it still faces challenges around delivery, safety, efficiency and unintended effects.

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Rare genetic condition: A disease caused by genetic changes that affects a relatively small number of people. Many rare diseases are serious, lifelong and difficult to diagnose without genomic testing.
Reference genome: A representative genome sequence used as a map for comparing, assembling and interpreting DNA from other individuals or species. Reference genomes are essential in human medicine, population genetics, biodiversity research and species conservation, but no single reference can capture all variation. A reference genome is not the final truth of a species. It is more like a very good map: useful, precious, occasionally missing a side road, and absolutely not the same thing as having walked every path yourself.
Reproductive cloning: Cloning intended to create a whole animal genetically very similar to another animal. This is different from cloning a gene in a lab.

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Secondary findings: Genetic results discovered during testing that were not the main reason for doing the test, but may still matter for health. For example, a genome test for one condition might unexpectedly find a variant linked to a different disease risk.
Short-read sequencing: A common DNA sequencing method that reads many small fragments of DNA and then uses computers to piece them together. It is fast, powerful and widely used in research and clinical genomics.
Single-cell sequencing: Sequencing methods that analyse DNA or RNA from individual cells rather than averaging signals across a whole tissue sample. Single-cell sequencing can reveal rare cell types, cell states, tumour diversity, immune responses and developmental processes that would otherwise be hidden.
Somatic cell nuclear transfer / SCNT: A cloning method where the nucleus from a body cell is placed into an egg cell whose own nucleus has been removed. This is the method used to create Dolly the sheep.
Somatic variant: A genetic variant that arises in a body cell during a person’s life rather than being inherited from a parent. Somatic variants are especially important in cancer, where tumours accumulate DNA changes that may help them grow, spread or resist treatment.
Spatial omics: Technologies that measure biological molecules, such as RNA or proteins, while preserving information about where they are located in a tissue. Spatial omics helps scientists see not only which genes are active, but where that activity is happening, which matters for cancer, development, brain research and tissue biology.
Synthetic biology: The design and engineering of biological systems for useful purposes. Synthetic biology can involve redesigning microbes, cells, genetic circuits or biological pathways to make medicines, materials, food ingredients, chemicals or other products.
Synthetic pathogen: A pathogen that has been created, reconstructed or substantially engineered using synthetic biology, DNA synthesis or genome-editing tools. The term matters because the same technologies that can help us study and prevent disease could also create serious biosecurity risks if used irresponsibly or maliciously.

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Therapeutic cloning: Cloning intended to create embryonic stem cells for research or possible medical use, rather than to create a whole cloned individual.
Transgenic organism: An organism that contains genetic material introduced from another species or from a designed genetic construct. Transgenic organisms are used in research, agriculture, medicine and biotechnology, but they often raise public concerns about safety, ecology, ownership and control.
Tumour genome: The genome of cancer cells in a tumour, including DNA changes that may not be present in the rest of the patient’s body. Sequencing a tumour genome can help identify mutations driving the cancer and may guide treatment, but it is not the same as sequencing the person’s inherited genome.

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Variant of uncertain significance: A variant of uncertain significance, often shortened to VUS, is a genetic change where we do not yet know whether it affects health. It is not the same as a diagnosis. It means: "we found something, but we do not yet know what it means."

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Whole exome sequencing: Whole exome sequencing, or WES, reads the protein-coding parts of the genome. These regions make up only a small part of all DNA, but they contain many variants known to cause genetic disease.
Whole genome sequencing: Whole genome sequencing, or WGS, reads almost the entire DNA sequence of an organism at once. In humans, it gives a broad view of the genome and can detect many types of genetic variation, including changes that may be missed by smaller tests.

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Zombie genome: A memorable way to describe genomic data that continues to exist and be used after the person it came from has died. Zombie genomes raise difficult questions about consent, withdrawal, relatives’ rights, medical findings and how long genomic data should remain in databases.

Common Terms and Concepts in Genomics