Early-onset Parkinson disease caused by a mutation in CHCHD2 and mitochondrial dysfunction.

Objective: Our goal was to identify the gene(s) associated with an early-onset form of Parkinson disease (PD) and the molecular defects associated with this mutation.

Methods: We combined whole-exome sequencing and functional genomics to identify the genes associated with early-onset PD. We used fluorescence microscopy, cell, and mitochondrial biology measurements to identify the molecular defects resulting from the identified mutation.

Results: Here, we report an association of a homozygous variant in , encoding coiled-coil-helix-coiled-coil-helix domain containing protein 2, a mitochondrial protein of unknown function, with an early-onset form of PD in a 26-year-old Caucasian woman. The mutation in PD patient fibroblasts causes fragmentation of the mitochondrial reticular morphology and results in reduced oxidative phosphorylation at complex I and complex IV. Although patient cells could maintain a proton motive force, reactive oxygen species production was increased, which correlated with an increased metabolic rate.

Conclusions: Our findings implicate in the pathogenesis of recessive early-onset PD, expanding the repertoire of mitochondrial proteins that play a direct role in this disease.