Re. Gene drives, the article points out (and links to [1]) a major issue, but doesn't quite give the full story on that issue. Resistance to gene drives will ar

Re. Gene drives, the article points out (and links to [1]) a major issue, but doesn't quite give the full story on that issue. Resistance to gene drives will arise, and isn't even that difficult to have happen. Key point: One source of this resistance is the CRISPR system itself, which uses an enzyme to cut a specific DNA sequence and insert whatever genetic code a researcher wants. Occasionally, however, cells sew the incision back together after adding or deleting random DNA letters. This can result in a sequence that the CRISPR gene-drive system no longer recognizes, halting the spread of the modified code. CRISPR/Cas9 is a nuclease, it cuts DNA. It does not stitch it back together, the cell does that afterwards. Sometimes that goes smoothly, other times it doesn't, but one thing that happens frequently when you cut DNA is mutation. It's why radiation exposure is bad, DNA breaks cause mutations. If mutations yield immunity, then something that depends on mutations NOT happening to keep operating, but itself CAUSES mutation, is unlikely to function for very long. [1] http://www.nature.com/news/gene-drives-thwarted-by-emergence-of-resistant-organisms-1.21397 http://www.nature.com/news/gene-drives-thwarted-by-emergence...