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Cohort

A group that is part of a clinical trial or study and is observed over a period of time.

Copy Number Variation (CNV)

Changes in the amount of a gene, whether by loss (deletion) or gain (amplification). Loss or gain of genes involved in growth or repair can cause cancer or modify the behavior of cancer.

Cytogenetic

The study of the structure, function, and abnormalities of human chromosomes.

De novo mutation

An alteration in a gene that is present for the first time in one family member as a result of a mutation in a germ cell (egg or sperm) of one of the parents, or a mutation that arises in the fertilized egg itself during early embryogenesis. Also called new mutation.

Epigenetics

The study of changes to DNA that do not drastically affect the DNA sequence directly but influence gene activity or expression. Epigenetic changes are changes in the way genes are switched on and off without changing the actual DNA sequence. They may be caused by age and exposure to environmental factors, such as diet, exercise, drugs, and chemicals.

Genomics

The study of the complete genetic material, including genes and their functions, of an organism.

Genotype

A specific variant or group of variants in an individual’s genetic code.

Genotyping

The process of determining differences in the genetic make-up of an individual by examining the individual’s DNA sequence using biological assays and comparing it to another individual’s sequence or a reference sequence.

Germline mutation

A gene change in a body’s reproductive cell (egg or sperm) that becomes incorporated into the DNA of every cell in the body of the offspring. Germline mutations are passed on from parents to offspring. Also called hereditary mutation.

Metabolism

The chemical changes that take place in a cell or an organism. These changes make energy and the materials that cells and organisms need to grow, reproduce, and stay healthy. Metabolism also helps get rid of toxic substances.

Molecular diagnostic testing

The process of identifying a disease by studying molecules, such as proteins, DNA, and RNA, in a tissue or fluid.

Mutation

A change in the usual DNA sequence at a particular gene locus. Mutations can be harmful, beneficial, or neutral in their effect on cell function.

Next-generation sequencing

A high-throughput method used to determine a portion of the nucleotide sequence of an individual’s genome. This technique utilizes DNA sequencing technologies that are capable of processing millions of DNA sequences in parallel. Also called massively parallel sequencing and NGS.

Personalized medicine

See precision medicine.

Polymorphism

A variation in DNA that is common in the germline of the human population (at least 1 percent of the population). The most common type of polymorphism is a single nucleotide polymorphism (SNP) in which one base of the DNA has changed. Most polymorphisms are inconsequential, but some can have harmful effects.

Precision medicine

A form of medicine that uses information about a person’s genes, proteins, and environment to prevent, diagnose, and treat disease. In cancer, personalized medicine uses specific information about a person’s tumor to help diagnose, plan treatment, find out how well treatment is working, or make a prognosis. Also called personalized medicine.

Proteome

The complete set of proteins made by an organism. Proteins are made in different amounts and at different times, depending on how they work, when they are needed, and how they interact with other proteins inside cells. Information about a proteome may be used to help find which proteins are involved in diseases, such as cancer. It may also be used to help develop drugs that block these proteins.

Signaling pathways

Describes a group of molecules in a cell that work together to control one or more cell functions, such as cell division or cell death. After the first molecule in a pathway receives a signal, it activates another molecule. This process is repeated until the last molecule is activated and the cell function is carried out. Abnormal activation of signaling pathways can lead to cancer, and drugs are being developed to block these pathways. These drugs may help block cancer cell growth and kill cancer cells.

Somatic mutation

An alteration in DNA that occurs after conception. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children. These alterations can (but do not always) cause cancer or other diseases. Most mutations in cancer are somatic mutations.

Targeted therapy

A type of treatment that uses drugs or other substances to identify and attack specific types of cancer cells with less harm to normal cells. Some targeted therapies block the action of certain enzymes, proteins, or other molecules involved in the growth and spread of cancer cells. Other types of targeted therapies help the immune system kill cancer cells or deliver toxic substances directly to cancer cells and kill them. Targeted therapy may have fewer side effects than other types of cancer treatment. Most targeted therapies are either small molecule drugs or monoclonal antibodies.

Tumor-suppressor genes

A type of gene that makes a protein called a tumor-suppressor protein that helps control cell growth. Loss of function mutations in tumor-suppressor genes may lead to cancer.