Polygenic inheritance plays a central role in Parkinson disease (PD). A priority in elucidating PD etiology lies in defining the biological basis of genetic risk. Unraveling how risk leads to disruption will yield disease-modifying therapeutic targets that may be effective. Here, we utilized a high-throughput and hypothesis-free approach to determine biological processes underlying PD using the largest currently available cohorts of genetic and gene expression data from International Parkinson’s Disease Genetics Consortium (IPDGC) and the Accelerating Medicines Partnership-Parkinson’s disease initiative (AMP-PD), among other sources. We applied large-scale gene-set specific polygenic risk score (PRS) analyses to assess the role of common variation on PD risk focusing on publicly annotated gene sets representative of curated pathways. We nominated specific molecular sub-processes underlying protein misfolding and aggregation, post-translational protein modification, immune response, membrane and intracellular trafficking, lipid and vitamin metabolism, synaptic transmission, endosomal–lysosomal dysfunction, chromatin remodeling and apoptosis mediated by caspases among the main contributors to PD etiology. We assessed the impact of rare variation on PD risk in an independent cohort of whole-genome sequencing data and found evidence for a burden of rare damaging alleles in a range of processes, including neuronal transmission-related pathways and immune response. We explored enrichment linked to expression cell specificity patterns using single-cell gene expression data and demonstrated a significant risk pattern for dopaminergic neurons, serotonergic neurons, hypothalamic GABAergic neurons, and neural progenitors. Subsequently, we created a novel way of building de novo pathways by constructing a network expression community map using transcriptomic data derived from the blood of PD patients, which revealed functional enrichment in inflammatory signaling pathways, cell death machinery related processes, and dysregulation of mitochondrial homeostasis. Our analyses highlight several specific promising pathways and genes for functional prioritization and provide a cellular context in which such work should be done.

Objective To investigate the safety and tolerability of convection‐enhanced delivery of an adeno‐associated virus, serotype‐2 vector carrying glial cell line‐derived neurotrophic factor into the bilateral putamina of PD patients. Methods Thirteen adult patients with advanced PD underwent adeno‐associated virus, serotype‐2 vector carrying glial cell line‐derived neurotrophic factor and gadoteridol (surrogate MRI tracer) coinfusion (450 μL/hemisphere) at escalating doses: 9 × 1010 vg (n = 6); 3 × 1011 vg (n = 6); and 9 × 1011 vg (n = 1). Intraoperative MRI monitored infusion distribution. Patients underwent UPDRS assessment and [18F]FDOPA‐PET scanning preoperatively and 6 and 18 months postoperatively. Results Adeno‐associated virus, serotype‐2 vector carrying glial cell line‐derived neurotrophic factor was tolerated without clinical or radiographic toxicity. Average putaminal coverage was 26%. UPDRS scores remained stable. Ten of thirteen and 12 of 13 patients had increased [18F]FDOPA Kis at 6 and 18 months postinfusion (increase range: 5–274% and 8–130%; median, 36% and 54%), respectively. Ki differences between baseline and 6‐ and 18‐month follow‐up were statistically significant (P < 0.0002). Conclusion Adeno‐associated virus, serotype‐2 vector carrying glial cell line‐derived neurotrophic factor infusion was safe and well tolerated. Increased [18F]FDOPA uptake suggests a neurotrophic effect on dopaminergic neurons. © 2019 International Parkinson and Movement Disorder Society

Objective This study was undertaken to compare the rate of change in cognition between glucocerebrosidase (GBA) mutation carriers and noncarriers with and without subthalamic nucleus deep brain stimulation (STN‐DBS) in Parkinson disease. Methods Clinical and genetic data from 12 datasets were examined. Global cognition was assessed using the Mattis Dementia Rating Scale (MDRS). Subjects were examined for mutations in GBA and categorized as GBA carriers with or without DBS (GBA+DBS+, GBA+DBS‐), and noncarriers with or without DBS (GBA‐DBS+, GBA‐DBS‐). GBA mutation carriers were subcategorized according to mutation severity (risk variant, mild, severe). Linear mixed modeling was used to compare rate of change in MDRS scores over time among the groups according to GBA and DBS status and then according to GBA severity and DBS status. Results Data were available for 366 subjects (58 GBA+DBS+, 82 GBA+DBS‐, 98 GBA‐DBS+, and 128 GBA‐DBS‐ subjects), who were longitudinally followed (range = 36–60 months after surgery). Using the MDRS, GBA+DBS+ subjects declined on average 2.02 points/yr more than GBA‐DBS‐ subjects (95% confidence interval [CI] = −2.35 to −1.69), 1.71 points/yr more than GBA+DBS‐ subjects (95% CI = −2.14 to −1.28), and 1.49 points/yr more than GBA‐DBS+ subjects (95% CI = −1.80 to −1.18). Interpretation Although not randomized, this composite analysis suggests that the combined effects of GBA mutations and STN‐DBS negatively impact cognition. We advise that DBS candidates be screened for GBA mutations as part of the presurgical decision‐making process. We advise that GBA mutation carriers be counseled regarding potential risks associated with STN‐DBS so that alternative options may be considered. ANN NEUROL 2022;91:424–435