Despite the loss of functional Parkinson’s disease, Koentjoro et al. demonstrated an asymptomatic homozygous carrier of the Parkin mutation who did not develop Parkinson’s disease in her seventh decade.116 In a follow-up study, they found that cells from the asymptomatic carrier showed NIX-mediated mitophagy and preserved mitochondrial function compared with cells from Parkin-related PD patients.117 Consistently, pharmacological induction of NIX restores mitophagy and mitochondrial function in cell lines derived from Parkin-related PD patients. Here, PRKN is linked to Parkinson disease.