Genome editing is a technique that lets scientists alter the DNA of plants, animals or humans more precisely than ever before, much like a biological cut-and-paste program.With gene editing, scientists home in on a piece of DNA and use molecular tools that act as scissors to snip that spot — deleting a defective gene, repairing it or replacing it.
Genome-editing technology offer promising tools to correct disease-genes by snipping away harmful mutations to possibly treat human diseases such as HIV/AIDS, haemophilia, sickle-cell anaemia and forms of cancer.
THE BIGGEST HURDLE
Safety is a key question because gene editing isn’t always precise enough; there’s the possibility of accidentally cutting DNA that’s similar to the real target. Out-of-body treatments like altering blood cells get around the fear of fixing one problem only to spark another, and efforts to improve precision are underway.
Ethical Controversies:
many researchers and ethicist fear that the technology used to make those manipulations might one day be “exploited for non-therapeutic modifications” such as selecting for intelligence and physical appearance. While gene editing technology may offer serious health opportunities, it also poses ethical questions, especially if scientists use it for reasons other than preventing illness or diseases for producing babies designed for better intellect, athleticism or appearance rather than to prevent disease.
Therefore, for Editing the DNA of Human Embryos It would be necessary to decide, for each potential application, whether the risks outweigh the possible benefit to a patient and shouldn’t be used for unethical purposes like making designer babies.
Editing human embryos is in conflict with evolution and the process of natural selection. It is welcome upto the point where in it is used to cure genetic disorders. But after that? The parents might want intelligent babies, might be willing to pay more for particular traits. Is this fair to the poor who can not afford this ? This will further the gap between the haves and the have not’s. Therefore a strict regulatory environment is necessary to keep up the spirit in which such innovations come to light.
If all turn to be intelligent what about menial jobs..
Lets produce another DNA who will always be there for menial jobs….. as if anyone would want to have unsuccessful babies….May be we ‘ll use Robots .. Ummm .. Really ? 
I personally feel,such a technology should be welcomed with regulations,otherwise it can be misused grossly.Many children are being born with genetic disorder,which is painful to the children and for the parents too.But given the economic disparity in the society.It should be allowed only in those cases,which deserves it and not in all cases.