虽然不同的Cas酶—包括经典的化脓性链球菌Cas9的变体（SpCas9）—可识别不同的PAM序列，但基因组的大部分仍然无法设靶编辑或更容易产生脱靶突变。

What happens next can vary. The standard Cas9 protein cuts the DNA at the target. When the cut is repaired, mutations are introduced that usually disable a gene. This is by far the most common use ...