Gene technology means changing or using genes. In genetic engineering, a gene from one organism is cut out and put into another so that it makes a useful product. Human insulin for people with diabetes is made by bacteria that carry the human insulin gene. It is identical to human insulin and can be made in large quantities.
Gene therapy aims to treat a genetic disorder such as cystic fibrosis by putting a working copy of a gene into a patient's cells, often using a virus as a vector. Embryos can also be screened for the genes that cause a serious inherited disease, so that it is not passed on. The main benefit is that inherited disorders could be treated or even cured.
There are practical risks. The new gene could be inserted in the wrong place, disrupt another gene and cause cancer. The body may have an immune reaction to the virus. The effect may not last, so the treatment may have to be repeated, and the long-term effects are not yet known.
There are also ethical considerations. Some people object to choosing the features of a baby, sometimes called designer babies. Changes made to embryos could be passed on to future generations. Treatments are expensive, so only wealthy people might afford them.