On the flip side, it's $600 for 30X WGS to find all those hundreds of off target mutations.
Joking aside, the weird part:
None of these DNA mutations were predicted by computer algorithms that are widely used by researchers to look for off-target effects.
An interesting, though definitely somewhat odd finding. If it's true, it'd undermine the current model of how CRISPR/Cas9 finds where and where not to cut in the genome. On the other, that goes against a lot of what's already been observed in cell lines taken out of the body. But maybe things really are really different in vivo.
In any case, CRISPR therapies are valued in the hundreds of millions of dollars each, so I have the feeling it won't be long until the answer to that is worked out. And even if the canonical Cas9 fails, there's also a dozen variants lined up with different mechanisms to reduce off target effects.