Genome engineering or gene editing is a technique where the DNA is added, removed, modified or replaced in the genome of a living organism.
CRISPR–Cas9 genome-editing technique is more precise in its operation as compared to earlier discovered tools and techniques for genome engineering.
Recently, a scientist from China claims to use this technology to disable a gene called CCR5 in human embryos and make the world's first genome-edited babies (Twin babies). This gene produces a protein which is needed for HIV to enter a cell (David Cyranoski and Heidi Ledford, Nature, 2018). Deletion of the CCR5 gene can thereby protect against HIV infection. It is currently (2019) one of the most discussed topics in the biological science community.