PRKN and Parkinson disease: Homozygous or compound heterozygous mutations of Parkinson protein 2, E3 ubiquitin protein ligase (PARK2) geneare cause (50% of cases) of autosomal recessive forms of PD, usually without atypical clinical features. PARK2 mutations also explain ~15% of the sporadic cases with onset before 45 [1, 2] and act as susceptibility alleles for late-onset forms of Parkinson disease (2% of cases) [3].