Following this discovery, several ethnically diverse individuals with early-onset PD (age <45 years) in other parts of the world were also found to carry Parkin mutations, which occur at a frequency of about 10–20 and 50% in sporadic and familial early-onset cases respectively (Lücking et al., 2000; Periquet et al., 2003; Mata et al., 2004). This evidence concerns the gene PRKN and Parkinson disease.