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Use this glossary to better understand the meaning of common terms used when referring to genetic diseases and treatment.

Adeno-associated viruses

A group of viruses able to get inside many different types of cells throughout the body.

Illustration of three different AAVs targeting different cell types within the human body


Sometimes called the “building blocks of life,” cells are structural, functional, and biological units of life. They contain the nucleus at their center, which holds a cell’s genetic materials. This is where genes are delivered for gene replacement therapy.

Illustration of cell within the human body

Deoxyribonucleic acid (DNA)

The carrier of the body’s genetic information, DNA contains the information used by the body to make every substance in our body, such as proteins. It is made up of 2 strands of molecules that wind around each other in a double helix, a structure like a twisted ladder.

Illustration of a double helix representing DNA

Gene replacement

Gene replacement uses a new, working gene to replace the function of a nonworking or missing gene. This gene then provides the instructions for the body to make the missing or insufficient protein.

Illustration of a vector entering the nucleus of a cell


The basic units of heredity, made up of DNA, genes carry the instructions cells need to make proteins used throughout the body.

Illustration of a double helix with the center representing a GENE

Gene addition

The addition of new therapeutic genes that target a specific cause of disease.  

Illustration of a double helix pair; one helix has a plus sign in the center where gene is located, and other helix has question mark in center where gene would be added

Gene editing

Also called genome editing, this treatment inserts, removes, or changes specific pieces of a person’s existing DNA to correct a gene mutation.

Illustration of a double helix with the center snipped

Gene inhibition

This treatment deactivates or “silences” the expression of a mutant gene that codes for a toxic protein or too much protein.

Illustration of a double helix with an exclamation point symbol in the center where gene is located

Gene therapy

Gene therapy is a treatment strategy for disorders caused by a missing or faulty gene and may involve addition, inhibition, editing, or functional replacement of a gene.

Illustration of a syringe with a double helix inside

Genetic disease

This type of disease is caused by a missing or nonworking gene or genes. It may be inherited from one or both parents, or can happen due to random errors. Monogenic genetic diseases are those caused by mutations in a single gene.

Illustration of a double helix with the center representing a Nonworking GENE


This is the control center of a cell and is where all of the cell’s genetic material, or DNA, is stored. This is also where the vector carries the new, working gene when undergoing gene replacement therapy.

Illustration of a CELL with the center NUCLEUS


A vehicle used to carry a working copy of a gene into the nucleus of a cell. It is usually made of a virus that has been changed so that it can no longer make a person sick.

Illustration of a double helix inside a hexagon representing a VECTOR