Gene therapy, science fiction or science fact?

The term gene therapy is commonly understood to be the use of DNA as apharmaceutical agent to treat diseases. This may be done by replacing defectiveor absent genes or to counteract those that are overexpressed. This would havebeen a science fiction story only a few years ago. Currently, gene therapy hasattracted considerable attention and has become a hot topic for investigation.Gene therapy aims to repair the cause of the problem and not merely suppresssymptoms, provides long-term cure, and does not require repeated applicationsor clinic visits.