If you know that you have a gene that will one day end your life early and there's a chance to shut the gene down, you should do it. Same thing goes for pregnancies and babies. If a defect is detected, turn the defect off and make sure the child is born healthy.
Yes, I believe that it is completely acceptable to enhance human beings with the use of genetic engineering. We've been technological since the dawn of man, always seeking ways to triumph over nature's limitations. Including our own physical limitations. Why stop now? Genetic manipulation to make us faster, better, and stronger is inevitable and should be acceptable.
Genetic engineering seems a lot like cheating. Usually, when we mess around with genetics, we make things worse. Look at processed food and how unhealthy that is for people. Letting things run their natural course is always better than interfering. Mother Nature will always be better at these things than us.
I do not think that we need to do anymore to humans than what nature has in store for us. Genetic enhancements other than things to get rid of some illnesses that children are born with will only cause more illnesses and diseases to come about. Every time one disease is cured a worse disease comes out. Enhancements will just get these started quicker.
It is not alright for genetic engineering to enhance human beings. This is too dangerous for humans to try to do. It is like people playing God and creating life. It could lead to trying to create the perfect specimens and the babies that are born but not wanted could be left to die.