Manal,
After hearing the various presentations at the gene therapy symposium in February, I have to say that it is anything but easy. The road to where they are now has been a long difficult road. Understanding the factors involved in making this happen, just makes this latest development even more encouraging. For gene therapy to work, a sufficient quantity of stem cells must be produced in the bone marrow so that a large enough quantity of the good genes can be implanted, so that the cells with the good beta thal genes can produce enough hemoglobin to free the patient from transfusions. These new good red blood cells must also be able to continue to reproduce in sufficient amounts to maintain the hemoglobin to a range of around 10. I believe we will soon see the fruits of these long years of research and development.