Livia Parodi, Mathieu Barbier, Maxime Jacoupy, Claire Pujol, François-Xavier Lejeune, Pauline Lallemant-Dudek, Typhaine Esteves, Maartje Pennings, Erik-Jan Kamsteeg, Marine Guillaud-Bataille, Guillaume Banneau, Giulia Coarelli, Badreddine Mohand Oumoussa, Matthew J. Fraidakis, Giovanni Stevanin, Christel Depienne, Bart van de Warrenburg, Alexis Brice, Alexandra Durr, Institut du Cerveau = Paris Brain Institute (ICM), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Sorbonne Université (SU)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Biologie mitochondriale – Mitochondrial biology, Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Bordeaux (UB), Radboud University Medical Center [Nijmegen], CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), Plateforme Post-génomique de la Pitié-Salpêtrière (PASS-P3S), Unité Mixte de Service Production et Analyse de données en Sciences de la vie et en Santé (PASS), Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU), 'Attikon' University Hospital, Universitätsklinikum Essen [Universität Duisburg-Essen] (Uniklinik Essen), Donders Institute for Brain, Cognition and Behaviour, Radboud University [Nijmegen], and We are deeply grateful to the patients for their participation. We thank the DNA and Cells Bank of the Paris Brain Institute (Institut du Cerveau, ICM) (Sylvie Forlani and Ludmila Jornea) and all the SPATAX network collaborators for their dedicated support: Mathieu Anheim, Dominique Bonneau, Rabab Debs, Claire Ewenczyk, Cyril Goizet, Solveig Heide, Isabelle Le Ber, Timothée Lenglet, Cecilia Marelli, Karine Nguyen, Diana Rodriguez, Tanya Stojkovic, Alina Maria Tataru, and Christine Tranchant.
Item does not contain fulltext PURPOSE: Hereditary spastic paraplegia type 4 is extremely variable in age at onset; the same variant can cause onset at birth or in the eighth decade. We recently discovered that missense variants in SPAST, which influences microtubule dynamics, are associated with earlier onset and more severe disease than truncating variants, but even within the early and late-onset groups there remained significant differences in onset. Given the rarity of the condition, we adapted an extreme phenotype approach to identify genetic modifiers of onset. METHODS: We performed a genome-wide association study on 134 patients bearing truncating pathogenic variants in SPAST, divided into early- and late-onset groups (aged ≤15 and ≥45 years, respectively). A replication cohort of 419 included patients carrying either truncating or missense variants. Finally, age at onset was analyzed in the merged cohort (N = 553). RESULTS: We found 1 signal associated with earlier age at onset (rs10775533, P = 8.73E-6) in 2 independent cohorts and in the merged cohort (N = 553, Mantel-Cox test, P < .0001). Western blotting in lymphocytes of 20 patients showed that this locus tends to upregulate SARS2 expression in earlier-onset patients. CONCLUSION: SARS2 overexpression lowers the age of onset in hereditary spastic paraplegia type 4. Lowering SARS2 or improving mitochondrial function could thus present viable approaches to therapy.