What are some results of genetic engineering that could improve a person's health

If future research produces more effective and accurate processes to manipulate human DNA, scientists will be able to create cures for diseases that are not curable today. Even birth defects could be almost totally eliminated if doctors were able to change a childs genes before birth. The process could also be adapted to cure hereditary diseases and prevent them from passing to future generations. It could also allow people with family histories of diseases, such as cancer, to "fix" their genetic predisposition to the disease.