CRISPR opens door to new type of medicine - genome surgery

Within a few years, Jim Johnsen and Delaney Van Riper may be among the first to benefit from CRISPR-Cas9 gene editing, a breakthrough that has already revolutionized biology research and promises to resurrect gene therapy.

UC San Francisco doctors working closely with UC Berkeley scientists plan to edit their genomes to correct rare genetic mutations and slow or halt progression of their diseases.

If successful, the trials will inaugurate a new era of "genome surgery" – the precision targeting of genetic defects in the genome, using CRISPR-Cas9 customized to individual patients. Such "bespoke" therapies can benefit small groups of individuals or families with particular genetic defects that would never be addressed by large pharmaceutical companies.

Johnsen and his family, including his daughter Greta, are carriers of a rare disorder, Best disease, that afflicts perhaps a thousand people nationwide and leads to early vision loss and eventual blindness, much like the more common macular degeneration.

Van Riper was born with a rare disease called Charcot-Marie-Tooth, which gradually destroys her nerve cells' ability to relay messages between her brain and muscles, causing her to slowly lose control of her limbs and her muscles to waste.

CRISPR-Cas9, invented at UC Berkeley, could make treating such diseases, if not easy, at least straightforward: with a large enough CRISPR toolbox, doctors can pick and choose the best approach and tailor a therapy to the specific genetic mutation.