Medical Genetics: Gene and Enzyme Replacement Therapy

Researchers are working on ways to treat genetic conditions. Two ways that have been shown to work are gene therapy and enzyme replacement therapy.

How does gene therapy work?

Gene therapy is a way to change the genes a person has. The therapy is done by inserting a normal gene that a person is missing or replacing a gene that is defective in some way.

An example of this type of therapy is for severe combined immunodeficiency disease (SCID). This is a very rare, life-threatening disease that a child may be born with. SCID causes a child to have very little or no immune system. This means they can’t fight normal infections. SCID is also known as the "boy in the bubble" syndrome. Living in a normal environment can cause death to a child with SCID. About 1 in 50,000 to 100,000 children is born with this disease.

Gene therapy for SCID is done by taking the child’s blood and putting the normal gene into the blood cells. The child is then given a blood transfusion with their own blood that has the normal gene inserted. The gene then works itself into the immune system and lessens the symptoms of the disorder. Gene therapy is currently being tested to treat several genetic conditions. But it is generally available only in clinical trials. Talk with your child’s healthcare provider about how to enroll your child in a clinical trial.

How does enzyme replacement therapy (ERT) work?

Enzymes help cause chemical reactions in the body. Some health conditions are caused by problems with the gene for an enzyme. One way to treat a genetic condition is to replace the enzyme.

An example of this type of therapy is for Gaucher disease. People with Gaucher disease have too much of a chemical called glucocerebroside. This is because of a lack of the enzyme glucocerebrosidase. It causes cells to form "Gaucher cells." Gaucher cells grow in place of healthy cells in several areas of the body. This causes a swollen belly due to large liver and spleen, loss of organ function, low levels of certain blood cells, and weakening and easily fractured bones.

ERT has been used to treat Gaucher disease to reverse the symptoms and improve the quality of life. ERT is a lifelong treatment. Stopping the treatment will cause the health problems to come back. A person getting this treatment must be under the care of a healthcare provider. This is to monitor the treatment for any adverse reactions and to change the dose as needed.

Talking with your healthcare provider

If you or your child has a genetic disorder, talk with your healthcare provider about whether these types of treatment may help.