Inserting working copies of a gene directly into the cells of a person with a genetic disorder is called gene therapy.

Here's a breakdown:

* Gene: The basic unit of heredity, responsible for carrying genetic information.

* Therapy: The treatment of disease or injury.

* Gene therapy: A technique that aims to treat or prevent disease by altering the genes inside a person's cells.

Gene therapy is a promising approach for treating a wide range of genetic disorders, including cystic fibrosis, sickle cell anemia, and muscular dystrophy.