CRISPR/Cas9 is a powerful editing tool that can cause serious side effects in the cells of human embyos prompting them to discard large chuncks of their genetic material. Researchers corrected mutations that cause systic fibrosis in cultured human stem cells. They used a technique called prime editing to replace the faulty piece of DNA with a healthy piece. CRISPR/Cas9 is faster, cheaper and more accurate than previous techniques of editing DNA.
Gene therapy replaces a faulty gene or adds a new gene in an attempt to cure disease or improve your body's ability to fight disease. It holds promise for treating a wide range of disease such as cystic fibrosis.