Sporadic PD risk has been attributed to a number of loci including regions of as yet unknown influence [62•, 63], as well as familial PD genes associated with mitochondrial dysfunction, e.g. Parkin, PINK1, ATP13A2, CHCHD2, SNCA, LRRK2 and GBA [64]. Here, CHCHD2 is linked to Parkinson disease.