Genome editing is a group of technologies that give scientists the ability to change an organism’s DNA. These technologies allow genetic material to be added, removed, or altered at particular locations in the genome. CRISPR-Cas9, which is short for “clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9”, is faster, cheaper, more accurate, and more efficient than other existing genome editing methods.
CRISPR-Cas9 was adapted from a naturally occurring genome editing system in bacteria. Researchers create a small piece of RNA with a short “guide” sequence that attaches to a specific target sequence of DNA in a genome. The RNA also binds to the Cas9 enzyme. The modified RNA is used to recognize the DNA sequence, and the Cas9 enzyme cuts the DNA at the targeted location. Once the DNA is cut, researchers use the cell’s own DNA repair machinery to add or delete pieces of genetic material, or to make changes to the DNA by replacing an existing segment with a customized DNA sequence.
The Food and Drug Administration has approved the first therapy to replace a faulty disease-causing gene with a healthy one. The injected gene therapy is designed to improve sight in people with an inherited