5 patients carried PRKN biallelic mutations (11% of monogenic PD, 2.3% of the cohort) and 6 subjects carried single pathogenic variants (in 2 subjects in association with VUS in other PD related genes); clinically, these patients had younger disease onset (mean 31.2 years, p < 0.05, with youngest onset at age 4 with clumsiness of gait and dystonia of the lower limbs due to PRKN homozygous mutation c.823C > T p.Arg275Trp [21]). This evidence concerns the gene PRKN and Parkinson disease.