Finally, the dosage of CRISPR affects the likelihood of the genome being riddled with unintended mutations. In general, the more Cas9 and guide RNA a cell gets and the longer those molecules hang around, the more likely it is that CRISPR will find slightly related but mismatched sequences and introduce off-target edits. The trick is to deliver just enough CRISPR into cells so that the right DNA target sequence gets edited, but no more than that.
