While I agree that all reasonable testing should be done, there comes a time in any new medical advance when human testing is inevitable; and there is always the risk of lost lives, including those procedures which are still experimental (where humans are concerned) that are intended to improve the chances of life in children. We cannot, unfortunately, eliminate all risk with this. What we can do, is to run as much testing as possible beforehand to work out as many of the problems as possible; there's also the fact that information sharing from other branches of genetic science can come into play here, to help understand why certain things happened here, and how to avoid them in future, if they can be avoided. There are many, many safety precautions to heed, and this is only now being discovered, really. So we've a long way to go before human testing will come about. But remember that in vitro fertilization, in its early days, often ended up disastrously. Various medications have produced terrible birth defects. But, because the nature of the universe is as it is, this is the way we learn, by painful trial and error -- sometimes horrendously painful. Take all the precautions we can, learn as much as we can, then when the time comes, do the best we can ... and pray.
