Genetic testing for Parkinson's disease in Israel: Insights from the Rostock Parkinson's Disease (ROPAD) study

We examined the yield of a large-scale genetic testing for patients with Parkinson's disease (PD) in Israel, where risk factor variants in GBA1 and/or the pathogenic p.Gly2019Ser variant in LRRK2 are prevalent among the Ashkenazi Jewish population. This study included data from all Israeli movement disorder clinics participating in the Rostock Parkinson's Disease (ROPAD) study. Patients were tested for variants in eight PD-related genes and 37 genes with possible phenotypic overlap. The sample consisted of 2699 PD patients recruited in three phases (1702 [63.1 %] males, mean age at onset 59.2 ± 10.6 years, 718 [26.6 %] with a family history of PD). Positive PD-relevant genetic test (PDGT) results were obtained in 512 participants (19.0 %). Among 187 (6.9 %) patients the results were due to pathogenic variants only in LRRK2, in 283 (10.5 %) due to risk factor variants only in GBA1, and another 15 patients (0.6 %) were carriers of variants in both genes. Twenty-six subjects (1.0 %) had a positive PDGT based on findings in PRKN (n = 19), PINK1 (n = 4), PARK7, SNCA, or VPS35 (one in each gene), and an additional patient had dual findings (GBA1 and SNCA). The most prevalent variants were LRRK2 p.Gly2019Ser and GBA1 p.Asn409Ser, detected in 191 (7.1 %) and 173 (6.4 %) patients, respectively. Excluding patients harboring only LRRK2 and/or GBA1 variants, the yield was 27/2214 (1.2 %). Seven participants, including one with a positive PDGT, had positive testing findings in genes related to dystonia (GCH1 and TOR1A) and dementia (MAPT). Genetic testing for Israeli PD patients is beneficial, while the yield is primarily attributed to LRRK2 and GBA1 variants.