Genetic medicine is a tough problem. CRISPR isn&#x27;t a panacea, and if I had to place bets, it&#x27;s primarily going to massively accelerate basic biological research rather than itself be a clinical tool except in certain limited contexts.<p>It&#x27;s pretty easy to edit a genome, just shoot some radiation at it. It&#x27;s a lot harder to do it precisely, and though CRISPR is a huge step in that direction, it&#x27;s not likely that in 10 years you&#x27;ll be able to walk into a doctor&#x27;s office and they&#x27;ll CRISPR that nagging genetic imperfection out of you.<p>CRISPR is a DNA nuclease, it cuts both strands of DNA at a site that is very precisely (though not perfectly) governed by an RNA template. If you cut both strands of a living thing&#x27;s DNA, that&#x27;s a Very Bad Thing for that organism. In fact, that&#x27;s why it evolved, as a tool for bacteria to combat viruses.<p>CRISPR based tools depend on reassembling that DNA properly, ideally with the desired alteration (inserting or deleting other pieces of DNA at the cut site). This works well if you have the opportunity to try a whole bunch of cells, and then can figure out which ones have the desired DNA modification.<p>In an R&amp;D context, that&#x27;s an easy bar to clear, but in the clinic that means you&#x27;re somewhat limited to things you can take out of the person, modify, multiply, and put back in the person. Often that means blood cells right now, but could eventually be adult stem cells. A huge advance to be sure, but many many diseases can&#x27;t be addressed this way.