Lanoiselée, Hélène-Marie, Nicolas, Gaël, Wallon, David, Rovelet-Lecrux, Anne, Lacour, Morgane, Rousseau, Stéphane, Richard, Anne-Claire, Pasquier, Florence, Rollin-Sillaire, Adeline, Martinaud, Olivier, Quillard-Muraine, Muriel, De La Sayette, Vincent, Boutoleau-Bretonnière, Claire, Etcharry-Bouyx, Frédérique, Chauviré, Valérie, Sarazin, Marie, Le Ber, Isabelle, Epelbaum, Stéphane, Jonveaux, Thérèse, Rouaud, Olivier, Ceccaldi, Mathieu, Felician, Olivier, Godefroy, Olivier, Formaglio, Maite, Croisile, Bernard, Auriacombe, Sophie, Chamard, Ludivine, Vincent, Jean-Louis, Sauvee, Mathilde, Marelli-Tosi, Cecilia, Gabelle, Audrey, Ozsancak, Canan, Pariente, Jérémie, Paquet, Claire, Hannequin, Didier, Campion, Dominique, CHU Lille, CNRS, Inserm, Université de Lille, Troubles cognitifs dégénératifs et vasculaires - U1171, Troubles cognitifs dégénératifs et vasculaires - U 1171 [TCDV], Génomique et Médecine Personnalisée du Cancer et des Maladies Neuropsychiatriques (GPMCND), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Service de neurologie [Rouen], CHU Rouen, Normandie Université (NU)-Normandie Université (NU), Centre Hospitalier Régional d'Orléans (CHRO), Service de génétique [Rouen], Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Département de neurologie [Lille], Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille), Troubles cognitifs dégénératifs et vasculaires - U 1171 - EA 1046 (TCDV), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lille, Droit et Santé-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille), Service de Neurologie [CHU Caen], Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Tumorothèque de Caen Basse-Normandie (TCBN), Service de neurologie [Nantes], Université de Nantes (UN)-Centre hospitalier universitaire de Nantes (CHU Nantes)-Hôpital Guillaume-et-René-Laennec [Saint-Herblain], Service de neurologie [Angers], Université d'Angers (UA)-Centre Hospitalier Universitaire d'Angers (CHU Angers), PRES Université Nantes Angers Le Mans (UNAM)-PRES Université Nantes Angers Le Mans (UNAM), Centre Hospitalier Sainte Anne [Paris], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), Institut du Cerveau et de la Moëlle Epinière = Brain and Spine Institute (ICM), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Service de neurologie [CHRU Nancy], Centre Hospitalier Régional Universitaire de Nancy (CHRU Nancy), Service de Neurologie générale, vasculaire et dégénérative (CHU de Dijon), Centre Hospitalier Universitaire de Dijon - Hôpital François Mitterrand (CHU Dijon), Institut de Neurosciences des Systèmes (INS), Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Service de neurologie et de neuropsychologie, Université de la Méditerranée - Aix-Marseille 2-Assistance Publique - Hôpitaux de Marseille (APHM)- Hôpital de la Timone [CHU - APHM] (TIMONE), Service de neurologie [Amiens], CHU Amiens-Picardie, Laboratoire de Neurosciences Fonctionnelles et Pathologies - UR UPJV 4559 (LNFP), Université de Picardie Jules Verne (UPJV), Service de Neurologie [Lyon], CHU Lyon, Service de neurologie [Bordeaux], CHU Bordeaux [Bordeaux]-Groupe hospitalier Pellegrin, Centre Hospitalier Régional Universitaire de Besançon (CHRU Besançon), Pôle Psychiatrie et Neurologie [Grenoble], Centre Hospitalier Universitaire [Grenoble] (CHU), Département de neurologie [Montpellier], Université Montpellier 1 (UM1)-Centre Hospitalier Régional Universitaire [Montpellier] (CHRU Montpellier)-Hôpital Gui de Chauliac [CHU Montpellier], Centre Hospitalier Régional Universitaire [Montpellier] (CHRU Montpellier)-Université de Montpellier (UM), Centre Hospitalier Universitaire de Toulouse (CHU Toulouse), Biomarqueurs CArdioNeuroVASCulaires (BioCANVAS), Université Paris 13 (UP13)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpital Lariboisière, Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpital Lariboisière-Fernand-Widal [APHP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Université Paris Diderot - Paris 7 (UPD7), Département de neurologie[Lille], Université de Lille, Droit et Santé-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille), Troubles cognitifs dégénératifs et vasculaires - U 1171 (TCDV), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lille-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille), Université Montpellier 1 (UM1)-Centre Hospitalier Régional Universitaire [Montpellier] (CHRU Montpellier)-Hôpital Gui de Chauliac [Montpellier]-Université de Montpellier (UM), CHU Toulouse [Toulouse], Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), Université Paris Diderot - Paris 7 (UPD7)-Hôpital Lariboisière-Fernand-Widal [APHP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Centre Hospitalier Régional d'Orléans (CHR), Troubles cognitifs dégénératifs et vasculaires (U1171), Université de Lille-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille)-INSERM, CHU Pitié-Salpêtrière [APHP], Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Pitié-Salpêtrière [APHP]-Centre National de la Recherche Scientifique (CNRS), Centre Hospitalier Régional Universitaire [Besançon] (CHRU Besançon), and Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpital Lariboisière-Université Paris Diderot - Paris 7 (UPD7)
Background Amyloid protein precursor (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2) mutations cause autosomal dominant forms of early-onset Alzheimer disease (AD-EOAD). Although these genes were identified in the 1990s, variant classification remains a challenge, highlighting the need to colligate mutations from large series. Methods and findings We report here a novel update (2012–2016) of the genetic screening of the large AD-EOAD series ascertained across 28 French hospitals from 1993 onwards, bringing the total number of families with identified mutations to n = 170. Families were included when at least two first-degree relatives suffered from early-onset Alzheimer disease (EOAD) with an age of onset (AOO) ≤65 y in two generations. Furthermore, we also screened 129 sporadic cases of Alzheimer disease with an AOO below age 51 (44% males, mean AOO = 45 ± 2 y). APP, PSEN1, or PSEN2 mutations were identified in 53 novel AD-EOAD families. Of the 129 sporadic cases screened, 17 carried a PSEN1 mutation and 1 carried an APP duplication (13%). Parental DNA was available for 10 sporadic mutation carriers, allowing us to show that the mutation had occurred de novo in each case. Thirteen mutations (12 in PSEN1 and 1 in PSEN2) identified either in familial or in sporadic cases were previously unreported. Of the 53 mutation carriers with available cerebrospinal fluid (CSF) biomarkers, 46 (87%) had all three CSF biomarkers—total tau protein (Tau), phospho-tau protein (P-Tau), and amyloid β (Aβ)42—in abnormal ranges. No mutation carrier had the three biomarkers in normal ranges. One limitation of this study is the absence of functional assessment of the possibly and probably pathogenic variants, which should help their classification. Conclusions Our findings suggest that a nonnegligible fraction of PSEN1 mutations occurs de novo, which is of high importance for genetic counseling, as PSEN1 mutational screening is currently performed in familial cases only. Among the 90 distinct mutations found in the whole sample of families and isolated cases, definite pathogenicity is currently established for only 77%, emphasizing the need to pursue the effort to classify variants., In a cohort including patients with familial Alzheimer disease as well as sporadic cases of early-onset Alzheimer disease, Dominique Campion and colleagues identify previously unreported mutations to PSEN1 and PSEN2., Author summary Why was this study done? Mutations in the amyloid protein precursor (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2) genes are a known cause of familial, early-onset Alzheimer disease (EOAD) (onset below age 65). However, in order to improve genetic counseling, it is necessary to report mutational screening from large cohorts of patients. What did the researchers do and find? In the present study, we performed sequencing of the APP, PSEN1, and PSEN2 genes in EOAD families and in 129 sporadic cases. Mutations were identified in 170 EOAD families and in 18 sporadic cases. In 10 sporadic cases, we showed that the mutation was absent in the parents, indicating that it occurred “de novo.” What do these findings mean? Sufficient evidence of pathogenicity is reached for 77% of the 90 distinct mutations identified in this sample, allowing their use in genetic counseling. Our results suggest a potential benefit to screening nonfamilial Alzheimer disease (AD) cases with onset before 50 y for APP, PSEN1, and PSEN2 mutations.