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1.  Reduced secreted clusterin as a mechanism for Alzheimer-associated CLU mutations 
Background
The clusterin (CLU) gene has been identified as an important risk locus for Alzheimer’s disease (AD). Although the actual risk–increasing polymorphisms at this locus remain to be identified, we previously observed an increased frequency of rare non-synonymous mutations and small insertion-deletions of CLU in AD patients, which specifically clustered in the β-chain domain of CLU. Nonetheless the pathogenic nature of these variants remained unclear.
Here we report a novel non-synonymous CLU mutation (p.I360N) in a Belgian Alzheimer patient and have explored the pathogenic nature of this and 10 additional CLU mutations on protein localization and secretion in vitro using immunocytochemistry, immunodetection and ELISAs.
Results
Three patient-specific CLU mutations in the β-chain (p.I303NfsX13, p.R338W and p.I360N) caused an alteration of the subcellular CLU localization and diminished CLU transport through the secretory pathway, indicative of possible degradation mechanisms. For these mutations, significantly reduced CLU intensity was observed in the Golgi while almost all CLU protein was exclusively present in the endoplasmic reticulum. This was further confirmed by diminished CLU secretion in HEK293T and HEK293 FLp-In cell lines.
Conclusions
Our data lend further support to the contribution of rare coding CLU mutations in the pathogenesis of neurodegenerative diseases. Functional analyses suggest reduced secretion of the CLU protein as the mode of action for three of the examined CLU mutations. One of those is a frameshift mutation leading to a loss of secreted protein, and the other two mutations are amino acid substitutions in the disulfide bridge region, possibly interfering with heterodimerization of the α- and β-chain of CLU.
Electronic supplementary material
The online version of this article (doi:10.1186/s13024-015-0024-9) contains supplementary material, which is available to authorized users.
doi:10.1186/s13024-015-0024-9
PMCID: PMC4502563  PMID: 26179372
Alzheimer’s disease; Clusterin; Mutations; Rare variant; β-chain; Cell secretion; Golgi
2.  Cerebrospinal Fluid P-Tau181P: Biomarker for Improved Differential Dementia Diagnosis 
The goal of this study is to investigate the value of tau phosphorylated at threonine 181 (P-tau181P) in the Alzheimer’s disease (AD) cerebrospinal fluid (CSF) biomarker panel for differential dementia diagnosis in autopsy confirmed AD and non-AD patients. The study population consisted of 140 autopsy confirmed AD and 77 autopsy confirmed non-AD dementia patients. CSF concentrations of amyloid-β peptide of 42 amino acids (Aβ1–42), total tau protein (T-tau), and P-tau181P were determined with single analyte ELISA-kits (INNOTEST®, Fujirebio, Ghent, Belgium). Diagnostic accuracy was assessed through receiver operating characteristic (ROC) curve analyses to obtain area under the curve (AUC) values and to define optimal cutoff values to discriminate AD from pooled and individual non-AD groups. ROC curve analyses were only performed on biomarkers and ratios that differed significantly between the groups. Pairwise comparison of AUC values was performed by means of DeLong tests. The Aβ1–42/P-tau181P ratio (AUC = 0.770) performed significantly better than Aβ1–42 (AUC = 0.677, P = 0.004), T-tau (AUC = 0.592, P < 0.001), and Aβ1–42/T-tau (AUC = 0.678, P = 0.001), while P-tau181P (AUC = 0.720) performed significantly better than T-tau (AUC = 0.592, P < 0.001) to discriminate between AD and the pooled non-AD group. When comparing AD and the individual non-AD diagnoses, Aβ1–42/P-tau181P (AUC = 0.894) discriminated AD from frontotemporal dementia significantly better than Aβ1–42 (AUC = 0.776, P = 0.020) and T-tau (AUC = 0.746, P = 0.004), while P-tau181P/T-tau (AUC = 0.958) significantly improved the differentiation between AD and Creutzfeldt-Jakob disease as compared to Aβ1–42 (AUC = 0.688, P = 0.004), T-tau (AUC = 0.874, P = 0.040), and Aβ1–42/P-tau181P (AUC = 0.760, P = 0.003). In conclusion, this study demonstrates P-tau181P is an essential component of the AD CSF biomarker panel, and combined assessment of Aβ1–42, T-tau, and P-tau181P renders, to present date, the highest diagnostic power to discriminate between AD and non-AD dementias.
doi:10.3389/fneur.2015.00138
PMCID: PMC4470274  PMID: 26136723
Alzheimer’s disease; dementia; differential diagnosis; biomarkers; cerebrospinal fluid; neuropathology; tau
3.  TDP-43 as a possible biomarker for frontotemporal lobar degeneration: a systematic review of existing antibodies 
Frontotemporal lobar degeneration (FTLD) is one of the leading causes of dementia after Alzheimer’s disease. A high-ranking candidate to become a diagnostic marker for a major pathological subtype of FTLD is the transactive response DNA binding protein of 43 kDa (TDP-43). The main objective is to elucidate which antibodies are specific for pathological TDP-43, with special interest in its modified isoforms. Indeed, TDP-43 has been shown to be hyperphosphorylated and truncated in disease. A secondary objective is to review existing immunoassays that quantify TDP-43 in biofluids. A systematic review of literature was performed by searching PubMed and Web of Science using predefined keywords. Of considered research papers the methods section was reviewed to select publications that enabled us to answer our learning objective. After quality assessment, antibody characteristics and related outcomes were extracted. We identified a series of well-characterized antibodies based on a scoring system that assessed the ability of each antibody to detect TDP-43 pathology. A selection of 29 unique antibodies was made comprising 10 high-ranking antibodies which were reported multiple times to detect TDP-43 pathology in both immunostaining and immunoblotting experiments and 19 additional antibodies which detected TDP-43 pathology but were only scored once. This systematic review provides an overview of antibodies that are reported to detect pathological TDP-43. These antibodies can be used in future studies of TDP-43 proteinopathies. Additionally, selected antibodies hold the potential to be used in the development of novel immunoassays for the quantification of TDP-43 in biofluids, as a possible biomarker for FTLD-TDP.
Electronic supplementary material
The online version of this article (doi:10.1186/s40478-015-0195-1) contains supplementary material, which is available to authorized users.
doi:10.1186/s40478-015-0195-1
PMCID: PMC4380254  PMID: 25853864
TDP-43; Antibodies; Immunoassay; Biomarkers; Frontotemporal lobar degeneration (FTLD)
4.  The monoaminergic footprint of depression and psychosis in dementia with Lewy bodies compared to Alzheimer’s disease 
Introduction
Depression and psychosis are two of the most severe neuropsychiatric symptoms (NPS) in dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD). Both NPS have negative effects on cognitive performance and life expectancy. The current study aimed to investigate and compare monoaminergic etiologies between both neurodegenerative conditions, given the lack of an efficient pharmacological treatment until present.
Methods
Eleven behaviorally relevant brain regions of the left frozen hemisphere of 10 neuropathologically confirmed AD patients with/without depression (AD + D/-D; 5 were psychotic within AD + D), 10 confirmed DLB patients, all of whom were depressed (DLB + D; 5 psychotic patients), and, finally, 10 confirmed control subjects were regionally dissected. All patients were retrospectively assessed before death using the Behavioral Pathology in Alzheimer’s Disease Rating Scale (Behave-AD) and Cornell Scale for Depression in Dementia amongst others. The concentrations of dopamine (DA), serotonin (5-HT), (nor)adrenaline and respective metabolites, i.e. 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), 5-hydroxy-3-indoleacetic acid (5-HIAA), and, 3-methoxy-4-hydroxyphenylglycol (MHPG), were determined using reversed-phase high-performance liquid chromatography with electrochemical detection.
Results
DLB subjects had the overall lowest monoamine and metabolite concentrations regarding 33 out of 41 significant monoaminergic group alterations. Moreover, MHPG levels were significantly decreased in almost 8 out of 11 brain regions of DLB- compared to AD patients. We also observed the lowest 5-HT and 5-HIAA levels, and 5-HIAA/5-HT turnover ratios in DLB + D compared to AD + D subjects. Additionally, a 4- and 7-fold increase of DOPAC/DA and HVA/DA turnover ratios, and, a 10-fold decrease of thalamic DA levels in DLB + D compared to AD + D patients and control subjects was noticed. Regarding psychosis, hippocampal DA levels in the overall DLB group significantly correlated with Behave-AD AB scores. In the total AD group, DA levels and HVA/DA ratios in the amygdala significantly correlated with Behave-AD AB scores instead.
Conclusions
Monoaminergic neurotransmitter alterations contribute differently to the pathophysiology of depression and psychosis in DLB as opposed to AD, with a severely decreased serotonergic neurotransmission as the main monoaminergic etiology of depression in DLB. Similarly, psychosis in DLB might, in part, be etiologically explained by dopaminergic alterations in the hippocampus, whereas in AD, the amygdala might be involved.
doi:10.1186/s13195-014-0090-1
PMCID: PMC4339739  PMID: 25717350
5.  Global investigation and meta-analysis of the C9orf72 (G4C2)n repeat in Parkinson disease 
Neurology  2014;83(21):1906-1913.
Objectives:
The objective of this study is to clarify the role of (G4C2)n expansions in the etiology of Parkinson disease (PD) in the worldwide multicenter Genetic Epidemiology of Parkinson's Disease (GEO-PD) cohort.
Methods:
C9orf72 (G4C2)n repeats were assessed in a GEO-PD cohort of 7,494 patients diagnosed with PD and 5,886 neurologically healthy control individuals ascertained in Europe, Asia, North America, and Australia.
Results:
A pathogenic (G4C2)n>60 expansion was detected in only 4 patients with PD (4/7,232; 0.055%), all with a positive family history of neurodegenerative dementia, amyotrophic lateral sclerosis, or atypical parkinsonism, while no carriers were detected with typical sporadic or familial PD. Meta-analysis revealed a small increase in risk of PD with an increasing number of (G4C2)n repeats; however, we could not detect a robust association between the C9orf72 (G4C2)n repeat and PD, and the population attributable risk was low.
Conclusions:
Together, these findings indicate that expansions in C9orf72 do not have a major role in the pathogenesis of PD. Testing for C9orf72 repeat expansions should only be considered in patients with PD who have overt symptoms of frontotemporal lobar degeneration/amyotrophic lateral sclerosis or apparent family history of neurodegenerative dementia or motor neuron disease.
doi:10.1212/WNL.0000000000001012
PMCID: PMC4248456  PMID: 25326098
6.  Rare mutations in SQSTM1 modify susceptibility to frontotemporal lobar degeneration 
van der Zee, Julie | Van Langenhove, Tim | Kovacs, Gabor G. | Dillen, Lubina | Deschamps, William | Engelborghs, Sebastiaan | Matěj, Radoslav | Vandenbulcke, Mathieu | Sieben, Anne | Dermaut, Bart | Smets, Katrien | Van Damme, Philip | Merlin, Céline | Laureys, Annelies | Van Den Broeck, Marleen | Mattheijssens, Maria | Peeters, Karin | Benussi, Luisa | Binetti, Giuliano | Ghidoni, Roberta | Borroni, Barbara | Padovani, Alessandro | Archetti, Silvana | Pastor, Pau | Razquin, Cristina | Ortega-Cubero, Sara | Hernández, Isabel | Boada, Mercè | Ruiz, Agustín | de Mendonça, Alexandre | Miltenberger-Miltényi, Gabriel | do Couto, Frederico Simões | Sorbi, Sandro | Nacmias, Benedetta | Bagnoli, Silvia | Graff, Caroline | Chiang, Huei-Hsin | Thonberg, Håkan | Perneczky, Robert | Diehl-Schmid, Janine | Alexopoulos, Panagiotis | Frisoni, Giovanni B. | Bonvicini, Christian | Synofzik, Matthis | Maetzler, Walter | vom Hagen, Jennifer Müller | Schöls, Ludger | Haack, Tobias B. | Strom, Tim M. | Prokisch, Holger | Dols-Icardo, Oriol | Clarimón, Jordi | Lleó, Alberto | Santana, Isabel | Almeida, Maria Rosário | Santiago, Beatriz | Heneka, Michael T. | Jessen, Frank | Ramirez, Alfredo | Sanchez-Valle, Raquel | Llado, Albert | Gelpi, Ellen | Sarafov, Stayko | Tournev, Ivailo | Jordanova, Albena | Parobkova, Eva | Fabrizi, Gian Maria | Testi, Silvia | Salmon, Eric | Ströbel, Thomas | Santens, Patrick | Robberecht, Wim | De Jonghe, Peter | Martin, Jean-Jacques | Cras, Patrick | Vandenberghe, Rik | De Deyn, Peter Paul | Cruts, Marc | Sleegers, Kristel | Van Broeckhoven, Christine
Acta Neuropathologica  2014;128(3):397-410.
Mutations in the gene coding for Sequestosome 1 (SQSTM1) have been genetically associated with amyotrophic lateral sclerosis (ALS) and Paget disease of bone. In the present study, we analyzed the SQSTM1 coding sequence for mutations in an extended cohort of 1,808 patients with frontotemporal lobar degeneration (FTLD), ascertained within the European Early-Onset Dementia consortium. As control dataset, we sequenced 1,625 European control individuals and analyzed whole-exome sequence data of 2,274 German individuals (total n = 3,899). Association of rare SQSTM1 mutations was calculated in a meta-analysis of 4,332 FTLD and 10,240 control alleles. We identified 25 coding variants in FTLD patients of which 10 have not been described. Fifteen mutations were absent in the control individuals (carrier frequency <0.00026) whilst the others were rare in both patients and control individuals. When pooling all variants with a minor allele frequency <0.01, an overall frequency of 3.2 % was calculated in patients. Rare variant association analysis between patients and controls showed no difference over the whole protein, but suggested that rare mutations clustering in the UBA domain of SQSTM1 may influence disease susceptibility by doubling the risk for FTLD (RR = 2.18 [95 % CI 1.24–3.85]; corrected p value = 0.042). Detailed histopathology demonstrated that mutations in SQSTM1 associate with widespread neuronal and glial phospho-TDP-43 pathology. With this study, we provide further evidence for a putative role of rare mutations in SQSTM1 in the genetic etiology of FTLD and showed that, comparable to other FTLD/ALS genes, SQSTM1 mutations are associated with TDP-43 pathology.
Electronic supplementary material
The online version of this article (doi:10.1007/s00401-014-1298-7) contains supplementary material, which is available to authorized users.
doi:10.1007/s00401-014-1298-7
PMCID: PMC4131163  PMID: 24899140
Sequestosome 1; SQSTM1; p62; FTLD; ALS; Rare variants
7.  A Multicenter Study of Glucocerebrosidase Mutations in Dementia With Lewy Bodies 
JAMA neurology  2013;70(6):10.1001/jamaneurol.2013.1925.
Importance
While mutations in glucocerebrosidase (GBA1) are associated with an increased risk for Parkinson disease (PD), it is important to establish whether such mutations are also a common risk factor for other Lewy body disorders.
Objective
To establish whether GBA1 mutations are a risk factor for dementia with Lewy bodies (DLB).
Design
We compared genotype data on patients and controls from 11 centers. Data concerning demographics, age at onset, disease duration, and clinical and pathological features were collected when available. We conducted pooled analyses using logistic regression to investigate GBA1 mutation carrier status as predicting DLB or PD with dementia status, using common control subjects as a reference group. Random-effects meta-analyses were conducted to account for additional heterogeneity.
Setting
Eleven centers from sites around the world performing genotyping.
Participants
Seven hundred twenty-one cases met diagnostic criteria for DLB and 151 had PD with dementia. We compared these cases with 1962 controls from the same centers matched for age, sex, and ethnicity.
Main Outcome Measures
Frequency of GBA1 mutations in cases and controls.
Results
We found a significant association between GBA1 mutation carrier status and DLB, with an odds ratio of 8.28 (95% CI, 4.78–14.88). The odds ratio for PD with dementia was 6.48 (95% CI, 2.53–15.37). The mean age at diagnosis of DLB was earlier in GBA1 mutation carriers than in noncarriers (63.5 vs 68.9 years; P<.001), with higher disease severity scores.
Conclusions and Relevance
Mutations in GBA1 are a significant risk factor for DLB. GBA1 mutations likely play an even larger role in the genetic etiology of DLB than in PD, providing insight into the role of glucocerebrosidase in Lewy body disease.
doi:10.1001/jamaneurol.2013.1925
PMCID: PMC3841974  PMID: 23588557
8.  Promoter DNA methylation regulates progranulin expression and is altered in FTLD 
Background
Frontotemporal lobar degeneration (FTLD) is a heterogeneous group of neurodegenerative diseases associated with personality changes and progressive dementia. Loss-of-function mutations in the growth factor progranulin (GRN) cause autosomal dominant FTLD, but so far the pathomechanism of sporadic FTLD is unclear.
Results
We analyzed whether DNA methylation in the GRN core promoter restricts GRN expression and, thus, might promote FTLD in the absence of GRN mutations. GRN expression in human lymphoblast cell lines is negatively correlated with methylation at several CpG units within the GRN promoter. Chronic treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (DAC) strongly induces GRN mRNA and protein levels. In a reporter assay, CpG methylation blocks transcriptional activity of the GRN core promoter. In brains of FTLD patients several CpG units in the GRN promoter are significantly hypermethylated compared to age-matched healthy controls, Alzheimer and Parkinson patients. These CpG motifs are critical for GRN promoter activity in reporter assays. Furthermore, DNA methyltransferase 3a (DNMT3a) is upregulated in FTLD patients and overexpression of DNMT3a reduces GRN promoter activity and expression.
Conclusion
These data suggest that altered DNA methylation is a novel pathomechanism for FTLD that is potentially amenable to targeted pharmacotherapy.
doi:10.1186/2051-5960-1-16
PMCID: PMC3893557  PMID: 24252647
5-aza-2′-deoxycytidine; DNA methylation; Epigenetics; FTLD; Progranulin
9.  APOE AND ALZHEIMER DISEASE: A MAJOR GENE WITH SEMI-DOMINANT INHERITANCE 
Molecular psychiatry  2011;16(9):903-907.
Apolipoprotein E (APOE) dependent lifetime risks (LTRs) for Alzheimer Disease (AD) are currently not accurately known and odds ratios (ORs) alone are insufficient to assess these risks. We calculated AD lifetime risk in 7,351 cases and 10,132 controls from Caucasian ancestry using Rochester (USA) incidence data. At the age of 85 the LTR of AD without reference to APOE genotype was 11% in males and 14% in females. At the same age, this risk ranged from 51% for APOE44 male carriers to 60% for APOE44 female carriers, and from 23% for APOE34 male carriers to 30% for APOE34 female carriers, consistent with semi-dominant inheritance of a moderately penetrant gene. Using PAQUID (France) incidence data, estimates were globally similar except that at age 85 the LTRs reached 68% and 35 % for APOE 44 and APOE 34 female carriers, respectively. These risks are more similar to those of major genes in Mendelian diseases, such as BRCA1 in breast cancer, than those of low-risk common alleles identified by recent GWAS in complex diseases. In addition, stratification of our data by age- groups clearly demonstrates that APOE4 is a risk factor not only for late- onset but for early- onset AD as well. Together, these results urge a reappraisal of the impact of APOE in Alzheimer disease.
doi:10.1038/mp.2011.52
PMCID: PMC3162068  PMID: 21556001
10.  The genetics and neuropathology of frontotemporal lobar degeneration 
Acta Neuropathologica  2012;124(3):353-372.
Frontotemporal lobar degeneration (FTLD) is a heterogeneous group of disorders characterized by disturbances of behavior and personality and different types of language impairment with or without concomitant features of motor neuron disease or parkinsonism. FTLD is characterized by atrophy of the frontal and anterior temporal brain lobes. Detailed neuropathological studies have elicited proteinopathies defined by inclusions of hyperphosphorylated microtubule-associated protein tau, TAR DNA-binding protein TDP-43, fused-in-sarcoma or yet unidentified proteins in affected brain regions. Rather than the type of proteinopathy, the site of neurodegeneration correlates relatively well with the clinical presentation of FTLD. Molecular genetic studies identified five disease genes, of which the gene encoding the tau protein (MAPT), the growth factor precursor gene granulin (GRN), and C9orf72 with unknown function are most frequently mutated. Rare mutations were also identified in the genes encoding valosin-containing protein (VCP) and charged multivesicular body protein 2B (CHMP2B). These genes are good markers to distinguish underlying neuropathological phenotypes. Due to the complex landscape of FTLD diseases, combined characterization of clinical, imaging, biological and genetic biomarkers is essential to establish a detailed diagnosis. Although major progress has been made in FTLD research in recent years, further studies are needed to completely map out and correlate the clinical, pathological and genetic entities, and to understand the underlying disease mechanisms. In this review, we summarize the current state of the rapidly progressing field of genetic, neuropathological and clinical research of this intriguing condition.
doi:10.1007/s00401-012-1029-x
PMCID: PMC3422616  PMID: 22890575
Frontotemporal lobar degeneration; Proteinopathy; MAPT; GRN; C9orf72; VCP; CHMP2B; Tau; TDP-43; FUS
11.  Recommendations for the treatment of epilepsy in adult patients in general practice in Belgium: an update 
Acta Neurologica Belgica  2012;112(2):119-131.
In 2008, a group of Belgian epilepsy experts published recommendations for antiepileptic drug (AED) treatment of epilepsies in adults and children. Selection of compounds was based on the registration and reimbursement status in Belgium, the level of evidence for efficacy, common daily practice and the personal views and experiences of the authors. In November 2011 the validity of these recommendations was reviewed by the same group of Belgian epilepsy experts who contributed to the preparation of the original paper. The recommendations made in 2008 for initial monotherapy in paediatric patients were still considered to be valid, except for the first choice treatment for childhood absence epilepsy. This update therefore focuses on the treatment recommendations for initial monotherapy and add-on treatment in adult patients. Several other relevant aspects of treatment with AEDs are addressed, including considerations for optimal combination of AEDs (rational polytherapy), pharmacokinetic properties, pharmacodynamic and pharmacokinetic interaction profile, adverse effects, comorbidity, treatment of elderly patients, AED treatment during pregnancy, and generic substitution of AEDs.
doi:10.1007/s13760-012-0070-9
PMCID: PMC3375006  PMID: 22544726
Epilepsy; Antiepileptic drugs; Seizures; Treatment; Recommendations
12.  Genetic and Clinical Features of Progranulin-Associated Frontotemporal Lobar Degeneration 
Archives of neurology  2011;68(4):488-497.
Objective
To assess the relative frequency of unique mutations and their associated characteristics in 97 individuals with mutations in progranulin (GRN), an important cause of frontotemporal lobar degeneration (FTLD).
Participants and Design
A 46-site International Frontotemporal Lobar Degeneration Collaboration was formed to collect cases of FTLD with TAR DNA-binding protein of 43-kDa (TDP-43)–positive inclusions (FTLD-TDP). We identified 97 individuals with FTLD-TDP with pathogenic GRN mutations (GRN+ FTLD-TDP), assessed their genetic and clinical characteristics, and compared them with 453 patients with FTLD-TDP in which GRN mutations were excluded (GRN− FTLD-TDP). No patients were known to be related. Neuropathologic characteristics were confirmed as FTLD-TDP in 79 of the 97 GRN+ FTLDTDP cases and all of the GRN− FTLD-TDP cases.
Results
Age at onset of FTLD was younger in patients with GRN+ FTLD-TDP vs GRN− FTLD-TDP (median, 58.0 vs 61.0 years; P<.001), as was age at death (median, 65.5 vs 69.0 years; P<.001). Concomitant motor neuron disease was much less common in GRN+ FTLDTDP vs GRN− FTLD-TDP (5.4% vs 26.3%; P<.001). Fifty different GRN mutations were observed, including 2 novel mutations: c.139delG (p.D47TfsX7) and c.378C>A (p.C126X). The 2 most common GRN mutations were c.1477C>T (p.R493X, found in 18 patients, representing 18.6% of GRN cases) and c.26C>A (p.A9D, found in 6 patients, representing 6.2% of cases). Patients with the c.1477C>T mutation shared a haplotype on chromosome 17; clinically, they resembled patients with other GRN mutations. Patients with the c.26C>A mutation appeared to have a younger age at onset of FTLD and at death and more parkinsonian features than those with other GRN mutations.
Conclusion
GRN+ FTLD-TDP differs in key features from GRN− FTLD-TDP.
doi:10.1001/archneurol.2011.53
PMCID: PMC3160280  PMID: 21482928
13.  Both common variations and rare non-synonymous substitutions and small insertion/deletions in CLU are associated with increased Alzheimer risk 
Background
We have followed-up on the recent genome-wide association (GWA) of the clusterin gene (CLU) with increased risk for Alzheimer disease (AD), by performing an unbiased resequencing of all CLU coding exons and regulatory regions in an extended Flanders-Belgian cohort of Caucasian AD patients and control individuals (n = 1930). Moreover, we have replicated genetic findings by targeted resequencing in independent Caucasian cohorts of French (n = 2182) and Canadian (n = 573) origin and by performing meta-analysis combining our data with previous genetic CLU screenings.
Results
In the Flanders-Belgian cohort, we identified significant clustering in exons 5-8 of rare genetic variations leading to non-synonymous substitutions and a 9-bp insertion/deletion affecting the CLU β-chain (p = 0.02). Replicating this observation by targeted resequencing of CLU exons 5-8 in 2 independent Caucasian cohorts of French and Canadian origin identified identical as well as novel non-synonymous substitutions and small insertion/deletions. A meta-analysis, combining the datasets of the 3 cohorts with published CLU sequencing data, confirmed that rare coding variations in the CLU β-chain were significantly enriched in AD patients (ORMH = 1.96 [95% CI = 1.18-3.25]; p = 0.009). Single nucleotide polymorphisms (SNPs) association analysis indicated the common AD risk association (GWA SNP rs11136000, p = 0.013) in the 3 combined datasets could not be explained by the presence of the rare coding variations we identified. Further, high-density SNP mapping in the CLU locus mapped the common association signal to a more 5' CLU region.
Conclusions
We identified a new genetic risk association of AD with rare coding CLU variations that is independent of the 5' common association signal identified in the GWA studies. At this stage the role of these coding variations and their likely effect on the β-chain domain and CLU protein functioning remains unclear and requires further studies.
doi:10.1186/1750-1326-7-3
PMCID: PMC3296573  PMID: 22248099
Alzheimer disease; clusterin gene (CLU); genomic resequencing; non-synonymous substitutions; insertions/deletions; β-chain domain; meta-analysis
14.  Common variants in ABCA7, MS4A6A/MS4A4E, EPHA1, CD33 and CD2AP are associated with Alzheimer’s disease 
Hollingworth, Paul | Harold, Denise | Sims, Rebecca | Gerrish, Amy | Lambert, Jean-Charles | Carrasquillo, Minerva M | Abraham, Richard | Hamshere, Marian L | Pahwa, Jaspreet Singh | Moskvina, Valentina | Dowzell, Kimberley | Jones, Nicola | Stretton, Alexandra | Thomas, Charlene | Richards, Alex | Ivanov, Dobril | Widdowson, Caroline | Chapman, Jade | Lovestone, Simon | Powell, John | Proitsi, Petroula | Lupton, Michelle K | Brayne, Carol | Rubinsztein, David C | Gill, Michael | Lawlor, Brian | Lynch, Aoibhinn | Brown, Kristelle S | Passmore, Peter A | Craig, David | McGuinness, Bernadette | Todd, Stephen | Holmes, Clive | Mann, David | Smith, A David | Beaumont, Helen | Warden, Donald | Wilcock, Gordon | Love, Seth | Kehoe, Patrick G | Hooper, Nigel M | Vardy, Emma R. L. C. | Hardy, John | Mead, Simon | Fox, Nick C | Rossor, Martin | Collinge, John | Maier, Wolfgang | Jessen, Frank | Schürmann, Britta | Rüther, Eckart | Heun, Reiner | Kölsch, Heike | van den Bussche, Hendrik | Heuser, Isabella | Kornhuber, Johannes | Wiltfang, Jens | Dichgans, Martin | Frölich, Lutz | Hampel, Harald | Hüll, Michael | Gallacher, John | Rujescu, Dan | Giegling, Ina | Goate, Alison M | Kauwe, John S K | Cruchaga, Carlos | Nowotny, Petra | Morris, John C | Mayo, Kevin | Sleegers, Kristel | Bettens, Karolien | Engelborghs, Sebastiaan | De Deyn, Peter P | Van Broeckhoven, Christine | Livingston, Gill | Bass, Nicholas J | Gurling, Hugh | McQuillin, Andrew | Gwilliam, Rhian | Deloukas, Panagiotis | Al-Chalabi, Ammar | Shaw, Christopher E | Tsolaki, Magda | Singleton, Andrew B | Guerreiro, Rita | Mühleisen, Thomas W | Nöthen, Markus M | Moebus, Susanne | Jöckel, Karl-Heinz | Klopp, Norman | Wichmann, H-Erich | Pankratz, V Shane | Sando, Sigrid B | Aasly, Jan O | Barcikowska, Maria | Wszolek, Zbigniew K | Dickson, Dennis W | Graff-Radford, Neill R | Petersen, Ronald C | van Duijn, Cornelia M | Breteler, Monique MB | Ikram, M Arfan | DeStefano, Anita L | Fitzpatrick, Annette L | Lopez, Oscar | Launer, Lenore J | Seshadri, Sudha | Berr, Claudine | Campion, Dominique | Epelbaum, Jacques | Dartigues, Jean-François | Tzourio, Christophe | Alpérovitch, Annick | Lathrop, Mark | Feulner, Thomas M | Friedrich, Patricia | Riehle, Caterina | Krawczak, Michael | Schreiber, Stefan | Mayhaus, Manuel | Nicolhaus, S | Wagenpfeil, Stefan | Steinberg, Stacy | Stefansson, Hreinn | Stefansson, Kari | Snædal, Jon | Björnsson, Sigurbjörn | Jonsson, Palmi V. | Chouraki, Vincent | Genier-Boley, Benjamin | Hiltunen, Mikko | Soininen, Hilkka | Combarros, Onofre | Zelenika, Diana | Delepine, Marc | Bullido, Maria J | Pasquier, Florence | Mateo, Ignacio | Frank-Garcia, Ana | Porcellini, Elisa | Hanon, Olivier | Coto, Eliecer | Alvarez, Victoria | Bosco, Paolo | Siciliano, Gabriele | Mancuso, Michelangelo | Panza, Francesco | Solfrizzi, Vincenzo | Nacmias, Benedetta | Sorbi, Sandro | Bossù, Paola | Piccardi, Paola | Arosio, Beatrice | Annoni, Giorgio | Seripa, Davide | Pilotto, Alberto | Scarpini, Elio | Galimberti, Daniela | Brice, Alexis | Hannequin, Didier | Licastro, Federico | Jones, Lesley | Holmans, Peter A | Jonsson, Thorlakur | Riemenschneider, Matthias | Morgan, Kevin | Younkin, Steven G | Owen, Michael J | O’Donovan, Michael | Amouyel, Philippe | Williams, Julie
Nature genetics  2011;43(5):429-435.
We sought to identify new susceptibility loci for Alzheimer’s disease (AD) through a staged association study (GERAD+) and by testing suggestive loci reported by the Alzheimer’s Disease Genetic Consortium (ADGC). First, we undertook a combined analysis of four genome-wide association datasets (Stage 1) and identified 10 novel variants with P≤1×10−5. These were tested for association in an independent sample (Stage 2). Three SNPs at two loci replicated and showed evidence for association in a further sample (Stage 3). Meta-analyses of all data provide compelling evidence that ABCA7 (meta-P 4.5×10−17; including ADGC meta-P=5.0×10−21) and the MS4A gene cluster (rs610932, meta-P=1.8×10−14; including ADGC meta-P=1.2×10−16; rs670139, meta-P=1.4×10−9; including ADGC meta-P=1.1×10−10) are novel susceptibility loci for AD. Second, we observed independent evidence for association for three suggestive loci reported by the ADGC GWAS, which when combined shows genome-wide significance: CD2AP (GERAD+ P=8.0×10−4; including ADGC meta-P=8.6×10−9), CD33 (GERAD+ P=2.2×10−4; including ADGC meta-P=1.6×10−9) and EPHA1 (GERAD+ P=3.4×10−4; including ADGC meta-P=6.0×10−10). These findings support five novel susceptibility genes for AD.
doi:10.1038/ng.803
PMCID: PMC3084173  PMID: 21460840
15.  TMEM106B is associated with frontotemporal lobar degeneration in a clinically diagnosed patient cohort 
Brain  2011;134(3):808-815.
In a genome-wide association study of frontotemporal lobar degeneration with pathological inclusions of TAR DNA-binding protein, significant association was obtained with three single nucleotide polymorphisms at 7p21.3, in a region encompassing the gene TMEM106B. This study also suggested a potential modifying effect of TMEM106B on disease since the association was strongest in progranulin mutation carriers. Further, the risk effect seemed to correlate with increased TMEM106B expression in patients. In the present study, we sought to replicate these three findings using an independent Flanders–Belgian cohort of primarily clinically diagnosed patients with frontotemporal lobar degeneration (n = 288). We were able to confirm the association with TMEM106B with a P-value of 0.008 for rs1990622, the top marker from the genome-wide association study [odds ratio 0.75 (95% confidence interval 0.61–0.93)]. Further, high-density single nucleotide polymorphism mapping suggested that the association was solely driven by the gene TMEM106B. Homozygous carriers of the TMEM106B protective alleles had a 50% reduced risk of developing frontotemporal lobar degeneration. However, we were unable to detect a modifying effect of the TMEM106B single nucleotide polymorphisms on onset age in progranulin mutation carriers belonging to an extended, clinical and pathological well-documented founder family segregating a progranulin null mutation. Also, we could not observe significant differences in messenger RNA expression between patients and control individuals in lymphoblast cell lines and in brain frontal cortex. In conclusion, we replicated the genetic TMEM106B association in a primarily clinically diagnosed cohort of patients with frontotemporal lobar degeneration from Flanders–Belgium. Additional studies are needed to unravel the molecular role of TMEM106B in disease onset and pathogenesis.
doi:10.1093/brain/awr007
PMCID: PMC3044834  PMID: 21354975
frontotemporal lobar degeneration; TMEM106B; genetic association; risk factor
16.  The CALHM1 P86L polymorphism is a genetic modifier of age at onset in Alzheimer’s disease: a meta-analysis study 
Lambert, Jean-Charles | Sleegers, Kristel | González-Pérez, Antonio | Ingelsson, Martin | Beecham, Gary W | Hiltunen, Mikko | Combarros, Onofre | Bullido, Maria J | Brouwers, Nathalie | Bettens, Karolien | Berr, Claudine | Pasquier, Florence | Richard, Florence | DeKosky, Steven T | Hannequin, Didier | Haines, Jonathan L | Tognoni, Gloria | Fiévet, Nathalie | Dartigues, Jean-François | Tzourio, Christophe | Engelborghs, Sebastiaan | Arosio, Beatrice | Coto, Elicer | De Deyn, Peter | Zompo, Maria Del | Mateo, Ignacio | Boada, Merce | Antunez, Carmen | Lopez-Arrieta, Jesus | Epelbaum, Jacques | Schjeide, Brit-Maren Michaud | Frank-Garcia, Ana | Giedraitis, Vilmentas | Helisalmi, Seppo | Porcellini, Elisa | Pilotto, Alberto | Forti, Paola | Ferri, Raffaele | Delepine, Marc | Zelenika, Diana | Lathrop, Mark | Scarpini, Elio | Siciliano, Gabriele | Solfrizzi, Vincenzo | Sorbi, Sandro | Spalletta, Gianfranco | Ravaglia, Giovanni | Valdivieso, Fernando | Vepsäläinen, Saila | Alvarez, Victoria | Bosco, Paolo | Mancuso, Michelangelo | Panza, Francesco | Nacmias, Benedetta | Bossù, Paola | Hanon, Olivier | Piccardi, Paola | Annoni, Giorgio | Mann, David | Marambaud, Philippe | Seripa, Davide | Galimberti, Daniela | Tanzi, Rudolph E | Bertram, Lars | Lendon, Corinne | Lannfelt, Lars | Licastro, Federico | Campion, Dominique | Pericak-Vance, Margaret A | Soininen, Hilkka | Van Broeckhoven, Christine | Alpérovitch, Annick | Ruiz, Agustin | Kamboh, M Ilyas | Amouyel, Philippe
The only established genetic determinant of non-Mendelian forms of Alzheimer’s disease (AD) is the ε4 allele of the apolipoprotein E gene (APOE). Recently, it has been reported that the P86L polymorphism of the calcium homeostasis modulator 1 gene (CALHM1) is associated with the risk of developing AD. In order to independently assess this association, we performed a meta-analysis of 7,873 AD cases and 13,274 controls of Caucasian origin (from a total of 24 centres in Belgium, Finland, France, Italy, Spain, Sweden, the UK and the USA). Our results indicate that the CALHM1 P86L polymorphism is likely not a genetic determinant of AD but may modulate age at onset by interacting with the effect of the ε4 allele of the APOE gene.
doi:10.3233/JAD-2010-100933
PMCID: PMC2964875  PMID: 20847397
17.  Diagnosis-Independent Alzheimer Disease Biomarker Signature in Cognitively Normal Elderly People 
Archives of neurology  2010;67(8):949-956.
Objective
To identify biomarker patterns typical for Alzheimer disease (AD) in an independent, unsupervised way, without using information on the clinical diagnosis.
Design
Mixture modeling approach.
Setting
Alzheimer’s Disease Neuroimaging Initiative database.
Patients or Other Participants
Cognitively normal persons, patients with AD, and individuals with mild cognitive impairment.
Main Outcome Measures
Cerebrospinal fluid–derived β-amyloid protein 1–42, total tau protein, and phosphorylated tau181P protein concentrations were used as biomarkers on a clinically well-characterized data set. The outcome of the qualification analysis was validated on 2 additional data sets, 1 of which was autopsy confirmed.
Results
Using the US Alzheimer’s Disease Neuroimaging Initiative data set, a cerebrospinal fluid β-amyloid protein 1–42/phosphorylated tau181P biomarker mixture model identified 1 feature linked to AD, while the other matched the “healthy” status. The AD signature was found in 90%, 72%, and 36% of patients in the AD, mild cognitive impairment, and cognitively normal groups, respectively. The cognitively normal group with the AD signature was enriched in apolipoprotein E ε4 allele carriers. Results were validated on 2 other data sets. In 1 study consisting of 68 autopsy-confirmed AD cases, 64 of 68 patients (94% sensitivity) were correctly classified with the AD feature. In another data set with patients (n = 57) with mild cognitive impairment followed up for 5 years, the model showed a sensitivity of 100% in patients progressing to AD.
Conclusions
The mixture modeling approach, totally independent of clinical AD diagnosis, correctly classified patients with AD. The unexpected presence of the AD signature in more than one-third of cognitively normal subjects suggests that AD pathology is active and detectable earlier than has heretofore been envisioned.
doi:10.1001/archneurol.2010.179
PMCID: PMC2963067  PMID: 20697045
18.  FUS pathology defines the majority of tau- and TDP-43-negative frontotemporal lobar degeneration 
Acta neuropathologica  2010;120(1):33-41.
Through an international consortium, we have collected 37 tau- and TAR DNA-binding protein 43 (TDP-43)-negative frontotemporal lobar degeneration (FTLD) cases, and present here the first comprehensive analysis of these cases in terms of neuropathology, genetics, demographics and clinical data. 92% (34/37) had fused in sarcoma (FUS) protein pathology, indicating that FTLD-FUS is an important FTLD subtype. This FTLD-FUS collection specifically focussed on aFTLD-U cases, one of three recently defined subtypes of FTLD-FUS. The aFTLD-U subtype of FTLD-FUS is characterised clinically by behavioural variant frontotemporal dementia (bvFTD) and has a particularly young age of onset with a mean of 41 years. Further, this subtype had a high prevalence of psychotic symptoms (36% of cases) and low prevalence of motor symptoms (3% of cases). We did not find FUS mutations in any aFTLD-U case. To date, the only subtype of cases reported to have ubiquitin-positive but tau-, TDP-43- and FUS-negative pathology, termed FTLD-UPS, is the result of charged multivesicular body protein 2B gene (CHMP2B) mutation. We identified three FTLD-UPS cases, which are negative for CHMP2B mutation, suggesting that the full complement of FTLD pathologies is yet to be elucidated.
doi:10.1007/s00401-010-0698-6
PMCID: PMC2887939  PMID: 20490813
FTLD; FUS; FTLD-UPS; Frontotemporal; FTD
19.  FUS pathology defines the majority of tau- and TDP-43-negative frontotemporal lobar degeneration 
Acta Neuropathologica  2010;120(1):33-41.
Through an international consortium, we have collected 37 tau- and TAR DNA-binding protein 43 (TDP-43)-negative frontotemporal lobar degeneration (FTLD) cases, and present here the first comprehensive analysis of these cases in terms of neuropathology, genetics, demographics and clinical data. 92% (34/37) had fused in sarcoma (FUS) protein pathology, indicating that FTLD-FUS is an important FTLD subtype. This FTLD-FUS collection specifically focussed on aFTLD-U cases, one of three recently defined subtypes of FTLD-FUS. The aFTLD-U subtype of FTLD-FUS is characterised clinically by behavioural variant frontotemporal dementia (bvFTD) and has a particularly young age of onset with a mean of 41 years. Further, this subtype had a high prevalence of psychotic symptoms (36% of cases) and low prevalence of motor symptoms (3% of cases). We did not find FUS mutations in any aFTLD-U case. To date, the only subtype of cases reported to have ubiquitin-positive but tau-, TDP-43- and FUS-negative pathology, termed FTLD-UPS, is the result of charged multivesicular body protein 2B gene (CHMP2B) mutation. We identified three FTLD-UPS cases, which are negative for CHMP2B mutation, suggesting that the full complement of FTLD pathologies is yet to be elucidated.
doi:10.1007/s00401-010-0698-6
PMCID: PMC2887939  PMID: 20490813
FTLD; FUS; FTLD-UPS; Frontotemporal; FTD
20.  Genome-wide association study identifies variants at CLU and PICALM associated with Alzheimer's disease, and shows evidence for additional susceptibility genes 
Harold, Denise | Abraham, Richard | Hollingworth, Paul | Sims, Rebecca | Gerrish, Amy | Hamshere, Marian | Singh Pahwa, Jaspreet | Moskvina, Valentina | Dowzell, Kimberley | Williams, Amy | Jones, Nicola | Thomas, Charlene | Stretton, Alexandra | Morgan, Angharad | Lovestone, Simon | Powell, John | Proitsi, Petroula | Lupton, Michelle K | Brayne, Carol | Rubinsztein, David C. | Gill, Michael | Lawlor, Brian | Lynch, Aoibhinn | Morgan, Kevin | Brown, Kristelle | Passmore, Peter | Craig, David | McGuinness, Bernadette | Todd, Stephen | Holmes, Clive | Mann, David | Smith, A. David | Love, Seth | Kehoe, Patrick G. | Hardy, John | Mead, Simon | Fox, Nick | Rossor, Martin | Collinge, John | Maier, Wolfgang | Jessen, Frank | Schürmann, Britta | van den Bussche, Hendrik | Heuser, Isabella | Kornhuber, Johannes | Wiltfang, Jens | Dichgans, Martin | Frölich, Lutz | Hampel, Harald | Hüll, Michael | Rujescu, Dan | Goate, Alison | Kauwe, John S.K. | Cruchaga, Carlos | Nowotny, Petra | Morris, John C. | Mayo, Kevin | Sleegers, Kristel | Bettens, Karolien | Engelborghs, Sebastiaan | De Deyn, Peter | van Broeckhoven, Christine | Livingston, Gill | Bass, Nicholas J. | Gurling, Hugh | McQuillin, Andrew | Gwilliam, Rhian | Deloukas, Panagiotis | Al-Chalabi, Ammar | Shaw, Christopher E. | Tsolaki, Magda | Singleton, Andrew | Guerreiro, Rita | Mühleisen, Thomas W. | Nöthen, Markus M. | Moebus, Susanne | Jöckel, Karl-Heinz | Klopp, Norman | Wichmann, H-Erich | Carrasquillo, Minerva M. | Pankratz, V. Shane | Younkin, Steven G. | Holmans, Peter | O'Donovan, Michael | Owen, Michael J. | Williams, Julie
Nature genetics  2009;41(10):1088-1093.
We undertook a two-stage genome-wide association study of Alzheimer's disease involving over 16,000 individuals. In stage 1 (3,941 cases and 7,848 controls), we replicated the established association with the APOE locus (most significant SNP: rs2075650, p= 1.8×10−157) and observed genome-wide significant association with SNPs at two novel loci: rs11136000 in the CLU or APOJ gene (p= 1.4×10−9) and rs3851179, a SNP 5′ to the PICALM gene (p= 1.9×10−8). Both novel associations were supported in stage 2 (2,023 cases and 2,340 controls), producing compelling evidence for association with AD in the combined dataset (rs11136000: p= 8.5×10−10, odds ratio= 0.86; rs3851179: p= 1.3×10−9, odds ratio= 0.86). We also observed more variants associated at p< 1×10−5 than expected by chance (p=7.5×10−6), including polymorphisms at the BIN1, DAB1 and CR1 loci.
doi:10.1038/ng.440
PMCID: PMC2845877  PMID: 19734902

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