Although thought of as a disease of old age, a small percentage of patients (about 5% of all cases) present with symptoms before the age of 60 years and the majority of these cases are caused by mutations in an ever increasing list of genes which affect either protein metabolism or mitochondrial function, including Pink1 (PARK6), Parkin (PARK 2), DJ-1 (PARK7) and alpha-synuclein (PARK 1), thus highlighting that dysfunction in either is sufficient to cause PD (Gasser et al., 2011). The gene discussed is PRKN; the disease is Parkinson disease.