Telomerase gene therapy seems to have extended mice lifetimes and improved health and age related diseases. They applied the therapy to adult mice, not embryos, and they used a DNA modified virus to deliver the therapy. The first linked article mentions an average life extension of 24%. The original article (EMBO Molecular Medicine) is here.
posted by aleph on Dec 9, 2012 - 40 comments

"But after five months, something clicked. The monkeys picked out red and green, again and again." UW researchers use gene therapy to give squirrel monkeys trichromatic vision. “Not only might we be able to cure disease, but we might engineer eyes with remarkable capabilities. You can imagine conferring enhanced night vision in normal eyes, or engineering genes that make photopigments with spectral properties for whatever you want your eye to see.”
posted by spitefulcrow on Sep 16, 2009 - 72 comments

A success for gene therapy to help hemophiliacs is announced. This is a first, but only time will tell if the treatment has a lasting effect and can be repeated. So far it's worked for only four of the six patients in the trial. The NY Times explains the research.
posted by caraig on Jun 7, 2001 - 5 comments

Scientists insert a jellyfish gene into a rhesus monkey. No word yet on how many asses the monkey has.
posted by plinth on Jan 11, 2001 - 15 comments