In human dermal fibroblasts, expression of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates antioxidant signaling, is increased in LRRK2 G2019S PD patients, but not non-PD-manifesting carriers, compared with control participants [84], suggesting mitochondrial oxidative stress vulnerability may be a mechanism underlying LRRK2 PD penetrance, at least with regard to the G2019S mutation. Here, LRRK2 is linked to Parkinson disease.