Accurate long-read sequencing identified GBA variants as a major genetic risk factor in the Luxembourg Parkinson’s study

Heterozygous variants in the glucocerebrosidase GBA gene are an increasingly recognized risk factor for Parkinson’s disease (PD). Due to the pseudogene GBAP1 that shares 96% sequence homology with the GBA coding region, accurate variant calling by array-based or short-read sequencing methods remains a major challenge in understanding the genetic landscape of GBA -related PD. We established a novel long-read sequencing technology for assessing the full length of the GBA gene. We used subsequent regression models for genotype-phenotype analyses. We sequenced 752 patients with parkinsonism and 806 healthy controls of the Luxembourg Parkinson’s study. All GBA variants identified showed a 100% true positive rate by Sanger validation. We found 12% of unrelated PD patients carrying GBA variants. Three novel variants of unknown significance (VUS) were identified. Using a structure-based approach, we defined a potential risk prediction method for VUS. This study describes the full landscape of GBA -related parkinsonism in Luxembourg, showing a high prevalence of GBA variants as the major genetic risk for PD. Our approach provides an important advancement for highly accurate GBA variant calling, which is essential for providing access to emerging causative therapies for GBA carriers. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The work presented here was funded by the Luxembourg National Research (FNR/NCER13/BM/11264123), the PEARL program (FNR/P13/6682797 to RK), MotaSYN (12719684 to RK), MAMaSyn (to RK), MiRisk‐PD (C17/BM/11676395 to RK, PM), the FNR/DFG Core INTER (ProtectMove, FNR11250962 to PM), and the PARK-QC DTU (PRIDE17/12244779/PARK-QC to RK, SP). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study has been approved by the National Research Ethics Committee (CNER Ref: 201407/13) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The dataset for this manuscript is not publicly available as it is linked to the Luxembourg Parkinson's Study and its internal regulations. Any requests for accessing the dataset can be directed to request.ncer-pd@uni.lu