david liu of the broad institut of harvd and mit, is working on tools and techniques that will, one day, lead to the safe gene editing of humans. (upbeat stcato music) he's developing a new gene editing tool called prime editing. can you tell me a little bit about your work in that regard? - so the machines that nature provides us, like cspr-cas9, often don't do what we want them to do. the result of breaking that double helix mostrequently disrupts genes, to cause the deletion or insertion of small numbers of dna letters at the cut site. (staccato electronic music) - [kondwani] both crispr and prime editing technologies work by cutting dna. but in some sensitive situations, crispr technology can be too blunt of a tool. that's because it breaks both strands of the double helix. in rare instances, this can disrupt the gene in unintended ways. but, prime editing is more like a pair of tweezers. it breaks only one strand of the double helix, allowing scientists to very precisely change a single base pair. this is like changing one note in a musical score. - for most diseases with a genetic