PARK7 and Parkinson disease: Nonetheless, in a series of elegant experiments using human-induced pluripotent stem-cell-derived DAergic neurons homozygous for a DJ-1 loss-of-function mutation, which in mouse models does not result in decreased nigral DA or α-synuclein aggregation and CRISPR–Cas9-mediated DJ-1 KO cells, the Krainc research team demonstrated that DA oxidation was sufficient to generate typical PD pathology [70].