Glucocerebrosidase Activity is not Associated with Parkinson's Disease Risk or Severity

Background Mutations in the GBA gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase), are risk factors for Parkinson's disease (PD). Objective To explore the association between GCase activity, PD phenotype, and probability for prodromal PD among carriers of mutations in the GBA and LRRK2 genes. Methods Participants were genotyped for the G2019S-LRRK2 and nine GBA mutations common in Ashkenazi Jews. Performance-based measures enabling the calculation of the Movement Disorder Society (MDS) prodromal probability score were collected. Results One hundred and seventy PD patients (102 GBA-PD, 38 LRRK2-PD, and 30 idiopathic PD) and 221 non-manifesting carriers (NMC) (129 GBA-NMC, 45 LRRK2-NMC, 15 GBA-LRRK2-NMC, and 32 healthy controls) participated in this study. GCase activity was lower among GBA-PD (3.15 +/- 0.85 mu mol/L/h), GBA-NMC (3.23 +/- 0.91 mu mol/L/h), and GBA-LRRK2-NMC (3.20 +/- 0.93 mu mol/L/h) compared to the other groups of participants, with no correlation to clinical phenotype. Conclusions Low GCase activity does not explain the clinical phenotype or risk for prodromal PD in this cohort. (c) 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society