What is a genetic disease?
Some genetic diseases are caused by a malfunctioning or missing gene or genes. Genes are made up of deoxyribonucleic acid (DNA) and come in pairs, one from each parent. Genes store the code—the information and instructions—the body needs to make proteins. Nearly every function of the body is made possible by proteins. When a piece of DNA is missing or changed, it can alter protein production. The protein may no longer be able to carry out its normal function. So even if a single protein is missing, in short supply, or made wrong, the effect on the body can be harmful.
A genetic disease can be passed down from one or both parents or can be a result of random errors in the body’s genes.
How can gene therapy help?
Gene therapy is an evolving strategy for disorders caused by a missing or faulty gene and may involve addition, inhibition, editing, or functional replacement of a gene.
Gene therapies can be one-time treatments and are designed to target the genetic root cause of diseases.


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.

Gene addition
Gene addition involves the introduction of a new gene into the body to target a specific aspect of what causes the disease.

Gene inhibition
Gene inhibition involves deactivating or “silencing” the expression of a mutated or faulty gene that codes for a toxic protein or too much protein.

Gene editing
Gene editing corrects the mutation in a gene that is causing disease.


Are gene therapies new?
Scientists have been investigating for decades how gene therapies can be used to treat genetic diseases.