Precision Medicine Glossary of Terms


A sign, such as a molecule in the blood or a genetic change, of a condition, disease, or a normal process in the human body. Biomarkers can be found in tissue, blood, urine, or other bodily fluids. They can be measured, and doctors use them to diagnose a condition, predict how it will progress, or choose the right treatment. Read all about biomarkers in our dedicated article.


A medical procedure in which a doctor takes a small amount of tissue or cells from the body to examine it under a microscope and look for signs of a disease. Biopsies are usually the best way to tell if someone has cancer, but they can also be used for other illnesses. Read more about biopsies here.

Chronic disease

A disease where symptoms persist for a long period of time, usually a year or more Chronic diseases tend to progress slowly and require constant medical attention. Most chronic diseases have no cure, but they can be managed with treatment and/or lifestyle changes. Some chronic diseases are life-threatening, but others are not.

Examples of chronic diseases include arthritis, diabetes, chronic kidney disease, asthma, and chronic obstructive pulmonary disease (COPD).

Clinical trial

Also called clinical study—a type of medical research that tests whether a new treatment, drug, diagnostic test, prevention, or screening method works for people.

Companion diagnostic

A medical device that helps doctors find out whether a specific drug will safely and effectively treat an individual patient and their condition. Companion diagnostics (or CDx for short) is commonly used in precision medicine together with biomarkers. It is called “companion” because it accompanies a therapeutic drug—doctors can use these devices to monitor if the drug works and how the person responds to it.

The devices are usually in vitro, or “in glass,” meaning that they involve things like test tubes or other, more complicated lab instruments.

Diagnostic test

Tests that doctors use to detect a disease, its cause, or the best treatment or drug for a specific patient and condition.

There are several tests that doctors use in precision medicine. Read all about diagnostic tests here.


Deoxyribonucleic acid (DNA) is a molecule that contains the genetic information that “tells” an organism how to develop, grow, and function. DNA is found inside cells.


A molecule that helps speed up normal processes in the body, like those related to cell metabolism. Most enzymes are proteins and they act as catalysts, accelerating the chemical reactions that cells need to stay healthy.


The “basic unit of inheritance” that passes from parent to child and contains information that’s needed to create individual physical traits, such as the color of one’s eyes. This information is carried in a sequence of DNA.

Gene therapy uses genes to treat various conditions. This is done by replacing missing or defective genes with healthy ones, turning some genes “on” or “off,” or correcting a genetic defect so that the gene can function well.


Traits or processes relating to a particular gene.


The entire DNA information contained within a cell. In addition to the genome, we also have an epigenome—the collection of chemical compounds, or chemical marks that change how genes in the genome work. These chemical marks in the epigenome can “tell” a gene what to do and when, switch genes on or off, or decide how much of a gene is expressed.


The study of genes and heredity, specifically the way that certain traits are passed down from one generation to the next. Genomics is the study of the entire DNA information contained within a cell (the genome).

This research helps medical professionals understand why some people get sick from certain viruses, bacteria, or environmental factors and behaviors (like smoking), while others don’t.


The genetic makeup of an individual organism.


Made up of elements or characteristics that are all different from one another. A group of patients can be heterogeneous (for example, when they have different characteristics such as age, gender, or socioeconomic status).

A disease can be heterogenous when it has many different causes or different subtypes. Tumors can be heterogenous, meaning that tumors of the same type can have diferent characteristics and different biomarkers. The diversity of all of these characteristics is called heterogeneity.


A type of treatment that helps boost your immune system to fight off cancer more effectively. Read more about immunotherapy and how it improves outcomes for people with cancer in our dedicated article.


The study of all chemical processes involving metabolites—small molecules that are the by-product of metabolic processes, for example, when your body breaks down food or a drug.


A change in an organism’s DNA sequence. For example, genetic mutations can happen when there are errors in how the cells divide and replicate or as a result of an infection.

Mutations occur in our bodies all the time, but most do not affect us and are not harmful at all. Sometimes, however, mutations can cause disease, as in the case of cancer

Next Generation Sequencing (NGS)

A new DNA and RNA-analyzing technology that has revolutionized cancer diagnosis and treatment. NGS is a so-called high-throughput technique, which means that it allows for hundreds of millions of DNA molecules to be sequenced at once.

This approach allows scientists to find genetic changes or mutations much faster and more accurately than previous, more traditional techniques.

Novel target

A molecule, protein, or receptor that has not previously been found or explored as a potential drug target.

Patient cohorts

A group of patients who share a common trait or condition. Patient cohorts are used to build comprehensive databases that contain clinical and molecular data from patients with specific diseases. These databases provide insights that drive research and the discovery of new drugs.

Patient subgroup/population

A specific group of people with common characteristics, such as age, gender, race, ethnicity, disease causes, or risk factors.


Short for “programmed death-ligand 1.” A protein found on the surface of some cancer cells and healthy immune cells.

PD-L1 plays a key role in how the immune system responds to cancer, so it is an important biomarker in many tumor types. Drugs called “immune checkpoint inhibitors” act on PD-L1 to help the immune system better fight off cancer.

Personalized medicine

Same as ‘precision medicine.’ A medical approach that makes decisions about a person’s diagnosis, treatment, or how they can prevent disease based on their genetic profile.


An important aspect of precision medicine that explores how a person’s DNA affects their response to a drug.


The set of observable traits in a person (such as height or hair color) that arises from a combination of their genotype and environmental factors, like nutrition or exercise.

Precision medicine

Same as personalized medicine. A medical approach that considers the unique genetic, environmental, and lifestyle characteristics of each patient in order to find or develop the most suitable treatment.

Precision oncology

An innovative approach that looks at the unique genetic characteristics of each type of cancer to choose the most effective, targeted treatment. Learn more about precision oncology here.


The study of the entirety of proteins within an organism or cell.

Rare diseases

Illnesses that affect a very small proportion of people (less than 5 in 10,000). However, collectively, a large number of people are affected by rare diseases (about 7% of the global population).

Real-World Evidence (RWE)

Scientific evidence about how a drug, medical device, treatment, or intervention works in the real world. Specifically, RWE looks at how a therapy is used, its safety, risks, and benefits.

Experts obtain this evidence by analyzing Real-World Data (RWD)—information about patients from sources like electronic health records or digital health tech.

RNA (ribonucleic acid)

A molecule that can be found in all living organisms. RNA is similar in structure to DNA, but unlike the latter (which has the famous structure of a double-stranded helix), RNA is made up of just one strand.


The techniques used to determine the sequence or primary structure of biological polymers—large molecules made from smaller, more basic chemical units. For example, DNA sequencing aims to determine the exact sequence or order of the four building blocks that make up a DNA molecule, called nucleotides.

Single nucleotide polymorphism (SNP)

A difference in a single nucleotide, a basic building block of DNA. A SNP (pronounced “snip”) is the most common variation in the human genome, and most SNPs do not affect health in any way.

Targeted therapy/treatment

A treatment or drug that is specifically designed or selected to target specific molecules. In cancer treatment, targeted therapy aims at molecules and proteins that cancer cells need to grow and multiply.


A genetic variant, or gene variant, refers to any difference in the DNA sequence that makes up a gene. A variant can be harmless (benign), pathogenic—meaning it creates a disease—or “of unknown significance.” A variant of unknown or uncertain significance (VUS) is a variant whose impact on human health is not yet known.