RAB32 Ser71Arg in autosomal dominant Parkinson's disease: linkage, association, and functional analyses

Emil K Gustavsson; Jordan Follett; Joanne Trinh; Sandeep K Barodia; Raquel Real; Zhiyong Liu; Melissa Grant-Peters; Jesse D Fox; Silke Appel-Cresswell; A Jon Stoessl; Alex Rajput; Ali H Rajput; Roland Auer; Russel Tilney; Marc Sturm; Tobias B Haack; Suzanne Lesage; Christelle Tesson; Alexis Brice; Carles Vilariño-Güell; Mina Ryten; Matthew S Goldberg; Andrew B West; Michele T Hu; Huw R Morris; Manu Sharma; Ziv Gan-Or; Bedia Samanci; Pawel Lis; Maria Teresa Periñan; Rim Amouri; Samia Ben Sassi; Faycel Hentati; Global Parkinson's Genetics Program (GP2); Francesca Tonelli; Dario R Alessi; Matthew J Farrer

doi:10.1016/S1474-4422(24)00121-2

RAB32 Ser71Arg in autosomal dominant Parkinson's disease: linkage, association, and functional analyses

Lancet Neurol. 2024 Apr 10:S1474-4422(24)00121-2. doi: 10.1016/S1474-4422(24)00121-2. Online ahead of print.

Authors

Emil K Gustavsson¹, Jordan Follett², Joanne Trinh³, Sandeep K Barodia⁴, Raquel Real⁵, Zhiyong Liu⁴, Melissa Grant-Peters⁶, Jesse D Fox⁷, Silke Appel-Cresswell⁸, A Jon Stoessl⁸, Alex Rajput⁹, Ali H Rajput⁹, Roland Auer¹⁰, Russel Tilney¹¹, Marc Sturm¹², Tobias B Haack¹², Suzanne Lesage¹³, Christelle Tesson¹³, Alexis Brice¹⁴, Carles Vilariño-Güell⁷, Mina Ryten¹⁵, Matthew S Goldberg⁴, Andrew B West¹⁶, Michele T Hu¹⁷, Huw R Morris⁵, Manu Sharma¹⁸, Ziv Gan-Or¹⁹, Bedia Samanci²⁰, Pawel Lis²¹, Maria Teresa Periñan²², Rim Amouri²³, Samia Ben Sassi²³, Faycel Hentati²³; Global Parkinson's Genetics Program (GP2); Francesca Tonelli²¹, Dario R Alessi²¹, Matthew J Farrer²⁴

Affiliations

¹ Department of Genetics and Genomic Medicine, Great Ormond Street Institute of Child Health, University College London, London, UK; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD, USA.
² McKnight Brain Institute, Department of Neurology, University of Florida, Gainesville, FL, USA; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
³ Institute of Neurogenetics, University of Lübeck, Lübeck, Germany; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
⁴ Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL, USA.
⁵ Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, UK; UCL Movement Disorders Centre, University College London, London, UK; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD, USA.
⁶ Department of Genetics and Genomic Medicine, Great Ormond Street Institute of Child Health, University College London, London, UK; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD, USA.
⁷ Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
⁸ Pacific Parkinson's Research Centre, Djavad Mowafaghian Centre for Brain Health, Division of Neurology, University of British Columbia, Vancouver, BC, Canada.
⁹ Movement Disorders Program, Division of Neurology, University of Saskatchewan and Saskatchewan Health Authority, Saskatoon, SK, Canada.
¹⁰ Department of Pathology, University of Saskatchewan and Saskatchewan Health Authority, Saskatoon, SK, Canada.
¹¹ Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London, UK; UCL Movement Disorders Centre, University College London, London, UK.
¹² Institute for Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.
¹³ Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, Inserm, CNRS, Paris, France.
¹⁴ Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, Inserm, CNRS, Paris, France; Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Département de Neurologie, Centre d'Investigation Clinique Neurosciences, DMU Neuroscience, Paris, France.
¹⁵ Department of Genetics and Genomic Medicine, Great Ormond Street Institute of Child Health, University College London, London, UK; NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, London, UK; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD, USA.
¹⁶ Duke Center for Neurodegeneration and Neurotherapeutics, Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
¹⁷ Division of Neurology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
¹⁸ Centre for Genetic Epidemiology, Institute for Clinical Epidemiology and Applied Biometry, University of Tübingen, Tübingen, Germany.
¹⁹ The Neuro, Montreal Neurological Institute-Hospital, Montreal, QC, Canada; Department of Neurology and Neurosurgery, and Department of Human Genetics, McGill University, Montreal, QC, Canada.
²⁰ Behavioural Neurology and Movement Disorders Unit, Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
²¹ MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, UK; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD, USA.
²² Queen Mary College, University of London, London, UK.
²³ Service de Neurologie, Institut National de Neurologie, La Rabta, Tunis, Tunisia.
²⁴ McKnight Brain Institute, Department of Neurology, University of Florida, Gainesville, FL, USA; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada. Electronic address: m.farrer@ufl.edu.

PMID: 38614108
DOI: 10.1016/S1474-4422(24)00121-2

Abstract

Background: Parkinson's disease is a progressive neurodegenerative disorder with multifactorial causes, among which genetic risk factors play a part. The RAB GTPases are regulators and substrates of LRRK2, and variants in the LRRK2 gene are important risk factors for Parkinson's disease. We aimed to explore genetic variability in RAB GTPases within cases of familial Parkinson's disease.

Methods: We did whole-exome sequencing in probands from families in Canada and Tunisia with Parkinson's disease without a genetic cause, who were recruited from the Centre for Applied Neurogenetics (Vancouver, BC, Canada), an international consortium that includes people with Parkinson's disease from 36 sites in 24 countries. 61 RAB GTPases were genetically screened, and candidate variants were genotyped in relatives of the probands to assess disease segregation by linkage analysis. Genotyping was also done to assess variant frequencies in individuals with idiopathic Parkinson's disease and controls, matched for age and sex, who were also from the Centre for Applied Neurogenetics but unrelated to the probands or each other. All participants were aged 18 years or older. The sequencing and genotyping findings were validated by case-control association analyses using bioinformatic data obtained from publicly available clinicogenomic databases (AMP-PD, GP2, and 100 000 Genomes Project) and a private German clinical diagnostic database (University of Tübingen). Clinical and pathological findings were summarised and haplotypes were determined. In-vitro studies were done to investigate protein interactions and enzyme activities.

Findings: Between June 1, 2010, and May 31, 2017, 130 probands from Canada and Tunisia (47 [36%] female and 83 [64%] male; mean age 72·7 years [SD 11·7; range 38-96]; 109 White European ancestry, 18 north African, two east Asian, and one Hispanic] underwent whole-exome sequencing. 15 variants in RAB GTPase genes were identified, of which the RAB32 variant c.213C>G (Ser71Arg) cosegregated with autosomal dominant Parkinson's disease in three families (nine affected individuals; non-parametric linkage Z score=1·95; p=0·03). 2604 unrelated individuals with Parkinson's disease and 344 matched controls were additionally genotyped, and five more people originating from five countries (Canada, Italy, Poland, Turkey, and Tunisia) were identified with the RAB32 variant. From the database searches, in which 6043 individuals with Parkinson's disease and 62 549 controls were included, another eight individuals were identified with the RAB32 variant from four countries (Canada, Germany, UK, and USA). Overall, the association of RAB32 c.213C>G (Ser71Arg) with Parkinson's disease was significant (odds ratio [OR] 13·17, 95% CI 2·15-87·23; p=0·0055; I²=99·96%). In the people who had the variant, Parkinson's disease presented at age 54·6 years (SD 12·75, range 31-81, n=16), and two-thirds had a family history of parkinsonism. RAB32 Ser71Arg heterozygotes shared a common haplotype, although penetrance was incomplete. Findings in one individual at autopsy showed sparse neurofibrillary tangle pathology in the midbrain and thalamus, without Lewy body pathology. In functional studies, RAB32 Arg71 activated LRRK2 kinase to a level greater than RAB32 Ser71.

Interpretation: RAB32 Ser71Arg is a novel genetic risk factor for Parkinson's disease, with reduced penetrance. The variant was found in individuals with Parkinson's disease from multiple ethnic groups, with the same haplotype. In-vitro assays show that RAB32 Arg71 activates LRRK2 kinase, which indicates that genetically distinct causes of familial parkinsonism share the same mechanism. The discovery of RAB32 Ser71Arg also suggests several genetically inherited causes of Parkinson's disease originated to control intracellular immunity. This shared aetiology should be considered in future translational research, while the global epidemiology of RAB32 Ser71Arg needs to be assessed to inform genetic counselling.

Funding: National Institutes of Health, the Canada Excellence Research Chairs program, Aligning Science Across Parkinson's, the Michael J Fox Foundation for Parkinson's Research, and the UK Medical Research Council.