PINK1 and Parkinson disease: However, loss-of-function mutations of PINK1 in vivo do not elicit the clinical symptoms of PD in monkeys [17], and our data further revealed that editing the PINK1 gene via the AAV9-delivered CRISPR/Cas9 system in the SN regions of adult monkeys only causes approximately 40% nigral dopaminergic cell loss (Fig. S1A, B).