The Potential of Gene Replacement Therapy for Genetic Diseases

For people affected by monogenic diseases, gene replacement therapy has the potential to help them in the future. As gene-based therapies are approved for genetic disorders, the advancements benefit all of those in the community now and further down the road.

People sitting in grass

Cystic fibrosis (CF)

CF is a genetic disease caused by mutations in the CFTR gene. The CFTR gene provides instructions for the body to make the protein needed for the production of normal, free-flowing mucus. When this gene is not working properly, cells that line the insides of the lungs, pancreas, and other organs make thick, sticky mucus. As a result, people with CF experience breathing problems and damage to airways, increased risk of lung infections, and digestive problems.

DMD Gene

Duchenne muscular dystrophy (DMD)

DMD is a genetic condition and is 1 of 9 types of muscular dystrophy. It is caused by mutations in the DMD gene and almost exclusively affects males. The DMD gene provides the body with instructions for making a protein called dystrophin, which is important to muscle cells. As a result, boys with DMD experience muscle weakness that appears in early childhood and quickly worsens. Boys with DMD may have delayed motor skills, often depend on a wheelchair by their teenage years, and may experience heart complications.

F8 and F9 Genes


Hemophilia is a genetic bleeding disease that mostly affects males. There are 2 major types, hemophilia A and hemophilia B. Hemophilia A is caused by changes in the F8 gene, while hemophilia B is caused by changes in the F9 gene. These genes are responsible for making important proteins that are needed for blood to clot properly after an injury. People with hemophilia may experience continuous bleeding after an injury or even spontaneously without an injury. Bleeding in the joints, muscles, brain, or internal organs can be especially dangerous.

HTT gene

Huntington’s disease

Huntington’s disease is a genetic disease that causes the progressive breakdown (degeneration) of nerve cells in the brain. It is caused by mutations on the huntingtin (HTT) gene. The HTT gene provides instructions for making a protein called huntingtin, which nerve cells (neurons) in the brain use to help them function. The symptoms of Huntington’s disease include uncontrolled movements, emotional problems, and loss of the ability to think and understand (cognition).

One of a number of genes

Genetic amyotrophic lateral sclerosis (ALS)

ALS is a rare disease that affects the nerve cells that control voluntary muscle movement. In most people, the cause of ALS is unknown. However, in some cases, ALS is genetic. Genetic ALS is caused by a single, nonworking gene. There are many different genes that, when they have an error, have been shown to cause ALS. Regardless of the genetic cause, over time, muscles lose their strength, and the disease can become life threatening.

MECP2 Gene

Rett syndrome (RTT)

RTT is a genetic disease that occurs mainly in girls and affects how the brain works and develops. It is caused by a mutation in a single gene called the MECP2 gene. Girls with RTT may sometimes appear to develop normally from the time they’re born up to about 18 months of age. After that, they quickly lose mental and physical abilities, and over time, they may lose the ability to speak, walk, and move.

SMN1 Gene

Spinal muscular atrophy (SMA)

SMA is a genetic condition that affects nerves and muscles. It is caused by a missing or nonworking SMN1 gene. The SMN1 gene is responsible for producing a protein that motor neuron cells need so they can tell the muscles what to do. When the SMN1 gene is nonworking or missing, these motor neuron cells stop working and die. Over time, muscles can become so weak that walking, eating, and breathing become difficult. This serious muscle weakness, especially in the muscles used to breathe, can be life threatening.