Based on the interpretation of genetic variants and on patients’ clinical features, a final diagnosis of monogenic PD was formulated in 43 patients (41.7% of patients carrying any genetic variant and 20% of the whole cohort, Table 2) with a significant prevalence of mutations in GBA1 (28/103 subjects, 12.8% of the whole cohort), followed by LRRK2 (10/103 patients, 9.7%), PRKN (5/103 patients, 4.8%). This evidence concerns the gene GBA1 and Parkinson disease.