Gene Editing - A New Frontier

By Glenn Petrie, Ph.D.
Senior Scientific Advisor
ABC Laboratories
www.abclabs.com

A new technology for “editing” genes has scientists excited about an entirely new method for treating disease. The CRISPR technique, along with other gene-editing technologies (TALENS, zinc finger nucleases) allow for the precise deletion of specific DNA sequences. CRISPR involve a Cas9 protein linked to an RNA strand. The RNA sequence serves to target the specific DNA sequence of interest and once bound the Cas9 enzyme cleaves both strands of the DNA.

Above graphic credit (link) to Scitechweb.com 

Since RNA synthesis is relatively cheap and easy this technology has exploded in the last 2 years. Feng Zhang and Eric Lander at MIT have created CRISPR libraries that target essentially the entire human genome. The promise of the technology is to delete genetic mutations and replace them with the correct genes.  Initial targets involve only a single mutation, e.g. sickle-cell anemia, progressing to diseases involving multiple mutations.

As with any new technology there are calls for caution. Chinese scientists reported attempts to repair defective genes in human embryos. This held up the specter of future “designer babies” enhanced in their embryonic stages. Others warn that this technology could be used to “weaponize” bacteria or viruses. Several prominent scientists have proposed a complete moratorium on gene editing until proper safeguards are in place.

Despite these concerns several biotech start-ups have been founded in the last 2 years including Intellia Therapeutics, Editas Medicine and Crispr Therapeutics. Successful in vitro results have been reported for the repair/modification of clinically important genes in hematopoietic stem cells, fibroblasts and T-cells. A quick internet search yields a number of companies offering their services to utilize CRISPR to perform gene editing in both cell lines and whole animals. Based on the extremely rapid advances in this area, gene-editing using CRISPR and other technologies promises to revolutionize our ability to manipulate the genome and attack genetic diseases.