I&#x27;m not an expert in this area, but I still don&#x27;t understand how you manage to reconcile site specific transgene insertion. In these studies reporter genes are clearly inserted and heritable. How is there anything more to the discussion?<p>Like, as reported by Doudna:<p><a href="http:&#x2F;&#x2F;science.sciencemag.org&#x2F;content&#x2F;337&#x2F;6096&#x2F;816.short" rel="nofollow">http:&#x2F;&#x2F;science.sciencemag.org&#x2F;content&#x2F;337&#x2F;6096&#x2F;816.short</a><p>&quot;We show here that in a subset of these systems, the mature crRNA that is base-paired to trans-activating crRNA (tracrRNA) forms a two-RNA structure that directs the CRISPR-associated protein Cas9 to introduce double-stranded (ds) breaks in target DNA. At sites complementary to the crRNA-guide sequence, the Cas9 HNH nuclease domain cleaves the complementary strand, whereas the Cas9 RuvC-like domain cleaves the noncomplementary strand. The dual-tracrRNA:crRNA, when engineered as a single RNA chimera, also directs sequence-specific Cas9 dsDNA cleavage.&quot;<p>Which part of that mechanism do you doubt? It sounds like you doubt the dsDNA nuclease activity of Cas9. Why not just order a plasmid, some Cas9 + gdna, put them together and sanger sequence your products? If Cas9 isn&#x27;t a site specific guided endonuclease you could prove it for $200.