Scientists have made the first known attempt to creating a genetically modified human embryo.
It involved changing the DNA of a large number of one-cell embryos,
using the gene editing technique called CRISPR.
This process was done for research purposes only.
None of the embryos were allowed to develop for more than a few days.
It only demonstrated that it is possible to correct defective genes that cause inherited disease.
The process is called 'germ line engineering'.
The genetically modified child would then pass on the changes to subsequent generations,
via their own germ cells, - the egg and the sperm-.
Some critics are worried, that this could open the flood gates to designer babies.
CRISPR editing is not always 100% successful.
In earlier experiments there were editing errors.
This is called as 'off-target' effects.
Also the desired DNA changes were not taken up, by all the cells of the embryo.
This effect is called mosaicism.
Latest experiments were able to overcome both these problems.
Human IVF embryos were created for the experiment, using the donated sperm of men,
carrying inherited disease mutations.
The scientists were able to overcome earlier difficulties,Â
by carrying out the CRISPR editing at the time they were fertilised by the sperm.
The experiment was earlier carried out in mice.
Scientists changed the coat colour of the mice, by editing one gene.
At present allowing an edited IVF embryo into a baby is not allowed in most countries.
However research is going on to further understand and improve the process.