Restricting our analysis to the four non-EOPD studies, that searched for biallelic carriers, demonstrated that single PRKN mutations were not associated with an increased PD risk in these cohorts (OR = 1.23, 95% CI: 0.55, 2.75, P = 0.614; I2 = 0.0%, Phet = 0.657; Supplementary Material, Fig. S3). This evidence concerns the gene PRKN and Parkinson disease.