Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as novel risk factors for Alzheimers Disease

The genetic component of Alzheimer’s disease (AD) has been mainly assessed using Genome Wide Association Studies (GWAS), which do not capture the risk contributed by rare variants. Here, we compared the gene-based burden of rare damaging variants in exome sequencing data from 32,558 individuals —16,036 AD cases and 16,522 controls— in a two-stage analysis. Next to known genes TREM2, SORL1 and ABCA7, we observed a significant association of rare, predicted damaging variants in ATP8B4 and ABCA1 with AD risk, and a suggestive signal in ADAM10. Next to these genes, the rare variant burden in RIN3, CLU, ZCWPW1 and ACE highlighted these genes as potential driver genes in AD-GWAS loci. Rare damaging variants in these genes, and in particular loss-of-function variants, have a large effect on AD-risk, and they are enriched in early onset AD cases. The newly identified AD-associated genes provide additional evidence for a major role for APP-processing, Aβ-aggregation, lipid metabolism and microglial function in AD

Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as risk factors for Alzheimer’s disease

Alzheimer’s disease (AD), the leading cause of dementia, has an estimated heritability of approximately 70%1. The genetic component of AD has been mainly assessed using genome-wide association studies, which do not capture the risk contributed by rare variants2. Here, we compared the gene-based burden of rare damaging variants in exome sequencing data from 32,558 individuals—16,036 AD cases and 16,522 controls. Next to variants in TREM2, SORL1 and ABCA7, we observed a significant association of rare, predicted damaging variants in ATP8B4 and ABCA1 with AD risk, and a suggestive signal in ADAM10. Additionally, the rare-variant burden in RIN3, CLU, ZCWPW1 and ACE highlighted these genes as potential drivers of respective AD-genome-wide association study loci. Variants associated with the strongest effect on AD risk, in particular loss-of-function variants, are enriched in early-onset AD cases. Our results provide additional evidence for a major role for amyloid-β precursor protein processing, amyloid-β aggregation, lipid metabolism and microglial function in AD

Étude descriptive d’une cohorte normande de neuropathies anti-mag‎ : aspects cliniques, électrophysiologiques et réponse aux traitements

Introduction et objectifs : La neuropathie démyélinisante associant une gammapathie monoclonale de type M (IgM) et des anticorps anti-Myelin-Associated Glycoprotein (MAG) est caractérisée par des paresthésies distales et une ataxie. Des cas atypiques sont rapportés. Les résultats des essais thérapeutiques sont hétérogènes et n’apportent pas de preuve suffisante pour recommander une molécule. Nos objectifs étaient de décrire une cohorte de patients atteints d’une neuropathie anti-MAG, sur le plan clinique, électrophysiologique et thérapeutique, de caractériser des profils électrocliniques particuliers et d’identifier des potentiels marqueurs d’efficacité des traitements. Patients et méthodes : L’étude, descriptive rétrospective multicentrique, portait sur une cohorte normande de patients atteints de neuropathie avec un taux spécifique d’anticorps anti-MAG, soit supérieur à 10000 BTU. Nous avons collecté systématiquement les données cliniques, électrophysiologiques, biologiques et les traitements effectués. Résultats : Vingt-quatre patients ont été inclus, avec une durée moyenne d’évolution de 7,9 ans. La présentation clinique était atypique pour 7 patients (29,3%). L’ENMG initial était typique chez 21 patients (91,3%), caractérisé par un allongement des latences distales. La présence d’un déficit moteur était un facteur de mauvais pronostic à long terme. Neuf patients (37,5%) nécessitaient une aide à la marche à la fin du suivi. Une efficacité clinique était observée après 10 traitements (23,8%). La discordance entre l’évolution post-thérapeutique clinique d’une part et celle de l’ENMG, des taux d’anticorps et d’IgM d’autre part était respectivement de 40%, 66,7% et 63,3%. Discussion et conclusion : Un dosage des anticorps anti-MAG est indiqué devant un profil ENMG typique, quelle que soit la présentation clinique. La prise en charge doit être discutée entre le neurologue et l'hématologue. Un contrôle post-thérapeutique des taux d’anti-MAG et d’IgM ne semblait pas apporter de bénéfice comme marqueur précoce d’efficacité

Telemedicine in French Memory Clinics During the COVID-19 Pandemic

International audienceThis multicenter study was conducted in French memory clinics during the first COVID-2019 lockdown (March-May 2020). The objective was to evaluate the effect of a telemedicine consultation on treatment modification in dementia care. Among 874 patients who had a telemedicine consultation, 103 (10.7%) had treatment modifications, in particular those living with a relative or diagnosed with Alzheimer's disease. A control group of patients referred March-May 2019 was also included. Treatment modification rate was similar between periods with an adjusted percentage difference of -4% (p = 0.27). Telemedicine consultations allowed treatment modifications with only a minor short-term negative impact on therapeutic strategies

Ageing stereotypes and prodromal Alzheimer’s disease (AGING): study protocol for an ongoing randomised clinical study

International audienceINTRODUCTION:The number of older people diagnosed with amnestic mild cognitive impairment (aMCI), the prodromal state of Alzheimer's disease (AD), is increasing worldwide. However, some patients with aMCI never convert to the AD type of dementia, with some remaining stable and others reverting to normal. This overdiagnosis bias has been largely overlooked and gone unexplained. There is ample evidence in the laboratory that negative ageing stereotypes (eg, the culturally shared belief that ageing inescapably causes severe cognitive decline) contribute to the deteriorating cognitive performances of healthy older adults, leading them to perform below their true abilities. The study described here is intended to test for the first time whether such stereotypes also impair patients' cognitive performances during neuropsychological examinations in memory clinics, resulting in overdiagnosis of aMCI.METHODS AND ANALYSIS:The ongoing study is a 4-year randomised clinical trial comparing patients' physiological stress and cognitive performances during neuropsychological testing in memory clinics. A total of 260 patients attending their first cognitive evaluation will be randomised to either a standard condition of test administration, assumed here to implicitly activate negative ageing stereotypes or a reduced-threat instruction condition designed to alleviate the anxiety arising from these stereotypes. Both groups will be tested with the same test battery and stress biomarkers. For 30 patients diagnosed with aMCI in each group (n=60), biomarkers of neurodegeneration and amyloidopathy will be used to distinguish between aMCI with normal versus abnormal AD biomarkers. A 9-month follow-up will be performed on all patients to identify those whose cognitive performances remain stable, deteriorate or improve.ETHICS AND DISSEMINATION:This protocol has been approved by the French National Agency for Medicines and Health Products Safety and the Sud-Est I French Ethics Committee (2017-A00946-47). Results will be published in peer-reviewed journals.TRIAL REGISTRATION NUMBER:NCT03138018

Telemedicine in French Memory Clinics During the COVID-19 Pandemic

International audienceThis multicenter study was conducted in French memory clinics during the first COVID-2019 lockdown (March-May 2020). The objective was to evaluate the effect of a telemedicine consultation on treatment modification in dementia care. Among 874 patients who had a telemedicine consultation, 103 (10.7%) had treatment modifications, in particular those living with a relative or diagnosed with Alzheimer's disease. A control group of patients referred March-May 2019 was also included. Treatment modification rate was similar between periods with an adjusted percentage difference of -4% (p = 0.27). Telemedicine consultations allowed treatment modifications with only a minor short-term negative impact on therapeutic strategies

Clinical and neuropathological diversity of tauopathy in MAPT duplication carriers

International audienceMicroduplications of the 17q21.31 chromosomal region encompassing the MAPT gene, which encodes the Tau protein, were identified in patients with a progressive disorder initially characterized by severe memory impairment with or without behavioral changes that can clinically mimic Alzheimer disease. The unique neuropathological report showed a primary tauopathy, which could not be unanimously classified in a given known subtype, showing both 4R- and 3R-tau inclusions, mainly within temporal cortical subregions and basal ganglia, without amyloid deposits. Recently, two subjects harboring the same duplication were reported with an atypical extrapyramidal syndrome and gait disorder. To decipher the phenotypic spectrum associated with MAPT duplications, we studied ten carriers from nine families, including two novel unrelated probands, gathering clinical (n = 10), cerebrospinal fluid (n = 6), MRI (n = 8), dopamine transporter scan (n = 4), functional (n = 5), amyloid (n = 3) and Tau-tracer (n = 2) PET imaging data as well as neuropathological examination (n = 4). Ages at onset ranged from 37 to 57 years, with prominent episodic memory impairment in 8/10 patients, associated with behavioral changes in four, while two patients showed atypical extrapyramidal syndrome with gait disorder at presentation, including one with associated cognitive deficits. Amyloid imaging was negative but Tau imaging showed significant deposits mainly in both mesiotemporal cortex. Dopaminergic denervation was found in 4/4 patients, including three without extrapyramidal symptoms. Neuropathological examination exclusively showed Tau-immunoreactive lesions. Distribution, aspect and 4R/3R tau aggregates composition suggested a spectrum from predominantly 3R, mainly cortical deposits well correlating with cognitive and behavioral changes, to predominantly 4R deposits, mainly in the basal ganglia and midbrain, in patients with prominent extrapyramidal syndrome. Finally, we performed in vitro seeding experiments in HEK-biosensor cells. Morphological features of aggregates induced by homogenates of three MAPT duplication carriers showed dense/granular ratios graduating between those induced by homogenates of a Pick disease and a progressive supranuclear palsy cases. These results suggest that MAPT duplication causes a primary tauopathy associated with diverse clinical and neuropathological features

Seizures in dominantly inherited Alzheimer disease

International audienceObjective: To assess seizure frequency in a large French cohort of autosomal dominant early- onset Alzheimer disease (ADEOAD) and to determine possible correlations with causative mutations.Methods: A national multicentric study was performed in patients with ADEOAD harboring a path- ogenic mutation within PSEN1, PSEN2, APP, or a duplication of APP, and a minimal follow-up of 5 years. Clinical, EEG, and imaging data were systematically recorded.Results: We included 132 patients from 77 families: 94 PSEN1 mutation carriers (MCs), 16 APP duplication carriers, 15 APP MCs, and 7 PSEN2 MCs. Seizure frequency was 47.7% after a mean follow-up of 8.4 years (range 5–25). After 5-year follow-up and using a Cox model analysis, the percentages of patients with seizures were respectively 19.1% (10.8%–26.7%) for PSEN1, 28.6% (0%–55.3%) for PSEN2, 31.2% (4.3%–50.6%) for APP duplications, and no patient for APP mutation. APP duplication carriers showed a significantly increased seizure risk compared to both APP MCs (hazard ratio [HR] 5 5.55 [95% confidence interval 1.87–16.44]) and PSEN1 MCs (HR 5 4.46 [2.11–9.44]). Among all PSEN1 mutations, those within the domains of protein hydrophilic I, transmembrane II (TM-II), TM-III, TM-IV, and TM-VII were associated with a significant increase in seizure frequency compared to other domains (HR 5 4.53 [1.93–10.65], p 5 0.0005)

Phenotype and imaging features associated with APP duplications

International audienceBackground: APP duplication is a rare genetic cause of Alzheimer disease and cerebral amyloid angiopathy (CAA). We aimed to evaluate the phenotypes of APP duplications carriers.Methods: Clinical, radiological, and neuropathological features of 43 APP duplication carriers from 24 French families were retrospectively analyzed, and MRI features and cerebrospinal fluid (CSF) biomarkers were compared to 40 APP-negative CAA controls.Results: Major neurocognitive disorders were found in 90.2% symptomatic APP duplication carriers, with prominent behavioral impairment in 9.7%. Symptomatic intracerebral hemorrhages were reported in 29.2% and seizures in 51.2%. CSF Aβ42 levels were abnormal in 18/19 patients and 14/19 patients fulfilled MRI radiological criteria for CAA, while only 5 displayed no hemorrhagic features. We found no correlation between CAA radiological signs and duplication size. Compared to CAA controls, APP duplication carriers showed less disseminated cortical superficial siderosis (0% vs 37.5%, p = 0.004 adjusted for the delay between symptoms onset and MRI). Deep microbleeds were found in two APP duplication carriers. In addition to neurofibrillary tangles and senile plaques, CAA was diffuse and severe with thickening of leptomeningeal vessels in all 9 autopsies. Lewy bodies were found in substantia nigra, locus coeruleus, and cortical structures of 2/9 patients, and one presented vascular amyloid deposits in basal ganglia.Discussion: Phenotypes associated with APP duplications were heterogeneous with different clinical presentations including dementia, hemorrhage, and seizure and different radiological presentations, even within families. No apparent correlation with duplication size was found. Amyloid burden was severe and widely extended to cerebral vessels as suggested by hemorrhagic features on MRI and neuropathological data, making APP duplication an interesting model of CAA