Identify a disease state that could be treated with gene therapy.

Hemophilia

Explanation:

Gene therapy can be used to replace, mutate, add a new gene in order to cure disease. Gene therapy can be used to treat many genetic disorders that cannot be cured by the help of medications.

The gene responsible for producing the clotting factor VIII (FVIII) or factor IX (FIX)  are inserted in the liver cells of the human body by the help of vector.

The gene responsible for producing the clotting factor VIII (FVIII) or factor IX (FIX) will start producing clotting factors and body will function properly.

This, is how gene therapy can be used to cure hemophilia.