We all thought that gene therapy will cure all our diseases.
All those hopes evaporated when Jesse Gelsinger died in 2000 of gene therapy. What unfolded after the incident was pretty bad. There were a lot of incidents of gene therapy that went bad and were never reported all over the country. And that put a lid to all the gene therapy experiments and made it a lot more harder to study it.
It is still very promising. There are patients who have been cured of certain diseases with gene therapy which would have killed them long back. There s a good documentary about Gelsinger in you tube.
Here is an article: http://www.actionbioscience.org/biotech/kolehmainen.html