Genes are the building blocks of inheritance. Passed from parent to child, they contain instructions for making proteins. If genes don't produce the right proteins or produce them correctly, a child can have a genetic disorder . Gene therapy is an experimental technique that uses genes to treat or prevent disease. The most common form of gene therapy involves inserting a normal gene to replace an abnormal gene. Other approaches include Swapping an abnormal gene for a normal one Repairing an abnormal gene Altering the degree to which a gene is turned on or off Although there is much hope for gene therapy, it is still experimental.