Although the population-based prevalence of PRKN-PD is largely unknown (Bruggemann and Klein, 1993), it is thought that PRKN mutations account for up to 50% of recessive familial forms and 80% in those patients with a PD onset before the age of 20 years (Corti et al., 2011). The gene discussed is PRKN; the disease is Parkinson disease.