Palacino et al. (2004) found a reduction of proteins from both complexes I and IV, correlating with a decreased respiratory capacity of mitochondria in PARK2 KO mice. Other studies, addressing OCR in the context of parkin dysfunction, have examined fibroblasts from PARK2 PD patients and reported contradictory results of decreased or increased basal and maximum OCR (Pacelli et al., 2011; Zanellati et al., 2015). Here, PRKN is linked to Parkinson disease.