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Aging is the strongest risk factor for Parkinson's disease (PD), which is a clinically heterogeneous movement disorder with highly variable age at onset. DNA methylation age (DNAm age) is an epigenetic clock that could reflect biological aging.The aim was to evaluate whether PD age at onset is associated with DNAm-age acceleration (difference between DNAm age and chronological age).We used the genome-wide Infinium MethylationEPIC array to assess DNAm age in discovery (n = 96) and replication (n = 182) idiopathic PD cohorts and a unique longitudinal LRRK2 cohort (n = 220) at four time points over a 3-year period, comprising 91 manifesting and 129 nonmanifesting G2019S carriers at baseline. Cox proportional hazard regression and multivariate linear regression were used to evaluate the relation between DNAm-age acceleration and PD age at onset, which was highly variable in manifesting G2019S carriers (36-75 years) and both idiopathic PD cohorts (26-77 and 35-81 years).DNAm-age acceleration remained steady over the 3-year period in most G2019S carriers. It was strongly associated with age at onset in the LRRK2 cohort (P = 2.25 × 10This study is the first to demonstrate that DNAm-age acceleration is related to PD age at onset, which could be considered in disease-modifying clinical trials. Future studies should evaluate the stability of DNAm-age acceleration over longer time periods, especially for phenoconverters from nonmanifesting to manifesting individuals. © 2022 International Parkinson and Movement Disorder Society.

BACKGROUND AND PURPOSE: Progressive supranuclear palsy (PSP) encompasses a broader range of disease courses than previously appreciated. The most frequent clinical presentations of PSP are Richardson syndrome (RS) and PSP with a predominant Parkinsonism phenotype (PSP-P). Time to reach gait dependence and cognitive impairment have been proposed as prognostic disease milestones. Genetic polymorphisms in TRIM11 and SLC2A13 genes have been associated with longer disease duration (DD). METHODS: Methods used include retrospective chart review, genetic single nucleotide polymorphism analyses (in three cases), and neuropathology. RESULTS: We identified four cases with long (>10–15 years) or very long (>15 years) DD. Stage 1 PSP tau pathology was present in two cases (one PSP-P and one undifferentiated phenotype), whereas pallidonigroluysian atrophy (PSP-RS) and Stage 4/6 (PSP-P) PSP pathology were found in the other two cases. Three cases were homozygous for the rs564309-C allele of the TRIM11 gene and the H1 MAPT haplotype. Two were heterozygous for rs2242367 (G/A) in SLC2A13, whereas the third was homozygous for the G-allele. CONCLUSIONS: We propose a protracted course subtype of PSP (PC-PSP) based on clinical or neuropathological criteria in two cases with anatomically restricted PSP pathology, and very long DD and slower clinical progression in the other two cases. The presence of the rs564309-C allele may influence the protracted disease course. Crystallizing the concept of PC-PSP is important to further understand the pathobiology of tauopathies in line with current hypotheses of protein misfolding, seeding activity, and propagation.

Background: Postoperative outcome following deep brain stimulation (DBS) of the subthalamic nucleus is variable, particularly with respect to axial motor improvement. We hypothesized a genetic underpinning to the response to surgical intervention, termed “surgicogenomics”. Objective: We aimed to identify genetic variants associated with clinical heterogeneity in DBS outcome of Parkinson’s disease (PD) patients that could then be applied clinically to target selection leading to improved surgical outcome. Methods: Retrospective clinical data was extracted from 150 patient’s charts. Each individual was genotyped using the genome-wide NeuroX array tailored to study neurologic diseases. Genetic data were clustered based on surgical outcome assessed by comparing pre- and post-operative scores of levodopa equivalent daily dose and axial impairment at one and five years post-surgery. Allele frequencies were compared between patients with excellent vs. moderate/poor outcomes grouped using a priori defined cut-offs. We analyzed common variants, burden of rare coding variants, and PD polygenic risk score. Results: NeuroX identified 2,917 polymorphic markers at 113 genes mapped to known PD loci. The gene-burden analyses of 202 rare nonsynonymous variants suggested a nominal association of axial impairment with 14 genes (most consistent with CRHR1, IP6K2, and PRSS3). The strongest association with surgical outcome was detected between a reduction in levodopa equivalent daily dose and common variations tagging two linkage disequilibrium blocks with SH3GL2. Conclusion: Once validated in independent populations, our findings may be implemented to improve patient selection for DBS in PD.

Age at onset of amyotrophic lateral sclerosis (ALS) is highly variable (eg, 27–74 years in carriers of the G4C2-expansion in C9orf72). It might be influenced by environmental and genetic factors via the modulation of DNA methylation (DNAm) at CpG-sites. Hence, we combined an epigenetic and genetic approach to test the hypothesis that some common single nucleotide polymorphisms (SNPs) at CpG-sites (CpG-SNPs) could modify ALS age of onset. Our genome-wide DNAm analysis suggested three CpG-SNPs whose DNAm levels are significantly associated with age of onset in 249 ALS patients (q C9orf72-carriers (n = 333; P = 0.025), suggesting that each A-allele delays onset by 1.6 years. Analysis of Genotype-Tissue Expression data revealed that the protective A-allele is linked with the reduced expression of CTSS in cerebellum (P = 0.00018), which is a critical brain region in the distributed neural circuits subserving motor control. CTSS encodes cathepsin S protein playing a key role in antigen presentation. In conclusion, we identified a 16 Kb locus tagged by rs4970944 as a modifier of ALS age of onset. Our findings support the role of antigen presenting processes in modulating age of onset of ALS and suggest potential drug targets (eg, CTSS). Future replication studies are encouraged to validate the link between the locus tagged by rs4970944 and age of onset in independent ALS cohorts, including different ethnic groups.

Background: Although genetic factors are known to contribute to neurodegenerative disease susceptibility, there remains a large amount of heritability unaccounted for across the diagnoses. Copy number variants (CNVs) contribute to these phenotypes, but their presence and influence on disease state remains relatively understudied. Methods: Here, we applied a depth of coverage approach to detect CNVs in 80 genes previously associated with neurodegenerative disease within participants of the Ontario Neurodegenerative Disease Research Initiative (n = 519). Results: In total, we identified and validated four CNVs in the cohort, including: (1) a heterozygous deletion of exon 5 in OPTN in an Alzheimer's disease participant; (2) a duplication of exons 1–5 in PARK7 in an amyotrophic lateral sclerosis participant; (3) a duplication of >3 Mb, which encompassed ABCC6, in a cerebrovascular disease (CVD) participant; and (4) a duplication of exons 7–11 in SAMHD1 in a mild cognitive impairment participant. We also identified 43 additional CNVs that may be candidates for future replication studies. Conclusion: The identification of the CNVs suggests a portion of the apparent missing heritability of the phenotypes may be due to these structural variants, and their assessment is imperative for a thorough understanding of the genetic spectrum of neurodegeneration.

Background:Essential tremor (ET) is a common movement disorder with ˜5% prevalence in individuals above the age of 65, but in rare cases, it arises during childhood. Growing evidence suggests the role of cerebellum in the disease mechanism. ET is highly heritable, however, poor replication of risk loci point to its significant heterogeneity. Thus, it is important to genetically investigate kindreds with a strong aggregation of ET.Methods:We conducted a clinical and whole-genome investigation of a large Caucasian Canadian family, in which six out of eight patients are affected by childhood-onset ET in four consecutive generations. Eight family members were available for study, including three patients affected by ET. Whole-genome sequencing (WGS) was conducted for the four most informative individuals, followed by Sanger sequencing in the entire kindred.Results:We searched for rare variants absent in the eldest unaffected individual, but present in the patients (two siblings and their third-degree relative). Our stringent whole-genome filtering approach revealed a rare heterozygous p. Arg90Gln substitution in TCP10L (rs151233771) in all three investigated patients. Sanger sequencing confirmed the p. Arg90Gln variant and revealed its absence in the rest of the family members.Conclusions:Whole-genome data of the family with ET resulted in a single candidate gene mapped to 21q22.11 locus (TCP10L) with the highest brain expression in cerebellum. Our study encourages future replication studies to validate the genetic link between TCP10L and ET, and suggests the p. Arg90Gln variant for functional investigation.

Multiple concussions, particularly in contact sports, have been associated with cognitive deficits, psychiatric impairment and neurodegenerative diseases like chronic traumatic encephalopathy. We used volumetric and deformation-based morphometric analyses to test the hypothesis that repeated concussions may be associated with smaller regional brain volumes, poorer cognitive performance and behavioural symptoms among former professional football players compared to healthy controls. This study included fifty-three retired Canadian Football League players, 25 age- and education-matched healthy controls, and controls from the Cambridge Centre for Aging and Neuroscience database for validation. Volumetric analyses revealed greater hippocampal atrophy than expected for age in former athletes with multiple concussions than controls and smaller left hippocampal volume was associated with poorer verbal memory performance in the former athletes. Deformation-based morphometry confirmed smaller bilateral hippocampal volume that was associated with poorer verbal memory performance in athletes. Repeated concussions may lead to greater regional atrophy than expected for age., Highlights • Age had a greater effect on hippocampal volume loss in athletes than in controls. • Years playing professional football related to smaller hippocampi and amygdalae. • Smaller hippocampal volume was related to lower verbal memory scores.

For many years there has been uncertainty regarding how apolipoprotein E (APOE) E2 and E4 variants may influence overlapping features of neurodegeneration, such as cognitive impairment. We aimed to identify whether the APOE variants are associated with cognitive function across various neurodegenerative and cerebrovascular diagnoses (n = 513). Utilizing a comprehensive neuropsychology battery, multivariate multiple regression was used to assess the influence of APOE carrier status and disease cohort on performance across five cognitive domains. Irrespective of disease cohort, E4 carriers had significantly lower performance in verbal memory and visuospatial domains than those with E3/3, while E2 carriers’ cognitive performance was not significantly different. However, E2 carriers with frontotemporal dementia (FTD) performed significantly worse than those with E3/3 in the attention/working memory, executive function, and visuospatial domains. Our results highlight that the influence of APOE variation on cognition is complex, in some cases varying based on diagnosis and possibly underlying disease pathology.

The repeat expansion in C9orf72 is the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia. C9orf72 patients present with a wide range in disease duration and age of onset. The strongest risk factor for both syndromes is aging, which was linked to DNA methylation (DNAm) age based on the cumulative assessment of the methylation levels of 353 CpGs included on the genome-wide 450k BeadChip. DNAm age may reflect biological age better than chronological age. We conducted a genome-wide blood DNA methylation study of 46 unrelated C9orf72 patients. After correction for multiple testing, none of the CpGs demonstrated association between its methylation level and disease duration or age of onset. However, we detected a significant reverse correlation of DNAm age-acceleration with disease duration and age of onset, suggesting that for every 5-year increase in DNAm age-acceleration there is a 3.2-year earlier age of onset and 1.5-year shorter disease duration. The significant correlations remain after adjusting for gender, TMEM106B genotypes, disease phenotype and C9orf72 5′CpG island methylation status. A similar trend was observed for the blood DNA of affected members of an extended C9orf72 family; and tissues from the central nervous system of C9orf72 autopsy cases. For instance, regression analysis suggested that a 5-year increase in DNAm age-acceleration is linked to an earlier age of onset by 4.7 or 5.5 years for frontal cortex or spinal cord, respectively. Blood DNAm age may be a useful biomarker for biological age, because blood DNAm age-acceleration was similar to all investigated brain tissues, except for cerebellum that ages more slowly. In conclusion, DNA methylation analysis of C9orf72 patients revealed that increased DNAm age-acceleration is associated with a more severe disease phenotype with a shorter disease duration and earlier age of onset. Electronic supplementary material The online version of this article (doi:10.1007/s00401-017-1713-y) contains supplementary material, which is available to authorized users.

Apolipoprotein E (APOE) E4 is the main genetic risk factor for Alzheimer's disease (AD). Due to the consistent association, there is interest as to whether E4 influences the risk of other neurodegenerative diseases. Further, there is a constant search for other genetic biomarkers contributing to these phenotypes, such as microtubule-associated protein tau (MAPT) haplotypes. Here, participants from the Ontario Neurodegenerative Disease Research Initiative were genotyped to investigate whether the APOE E4 allele or MAPT H1 haplotype are associated with five neurodegenerative diseases: (1) AD and mild cognitive impairment (MCI), (2) amyotrophic lateral sclerosis, (3) frontotemporal dementia (FTD), (4) Parkinson's disease, and (5) vascular cognitive impairment.Genotypes were defined for their respective APOE allele and MAPT haplotype calls for each participant, and logistic regression analyses were performed to identify the associations with the presentations of neurodegenerative diseases.Our work confirmed the association of the E4 allele with a dose-dependent increased presentation of AD, and an association between the E4 allele alone and MCI; however, the other four diseases were not associated with E4. Further, the APOE E2 allele was associated with decreased presentation of both AD and MCI. No associations were identified between MAPT haplotype and the neurodegenerative disease cohorts; but following subtyping of the FTD cohort, the H1 haplotype was significantly associated with progressive supranuclear palsy.This is the first study to concurrently analyze the association of APOE isoforms and MAPT haplotypes with five neurodegenerative diseases using consistent enrollment criteria and broad phenotypic analysis.Étude de variance génétique dans le cadre de l'initiative de recherche sur les maladies neurodégénératives en Ontario. Contexte/Objectif : L’apolipoprotéine E4 (ApoE4) constitue le principal facteur de risque génétique de la maladie d’Alzheimer. En raison de cette association systématique, il existe un intérêt certain à savoir dans quelle mesure cette classe d’apolipoprotéines peut influencer le risque d’autres maladies neurodégénératives. En outre, le milieu de la recherche n’a de cesse d’identifier d’autres biomarqueurs génétiques, par exemple les haplotypes H1 de la protéine tau associée aux microtubules, qui contribuent à certains phénotypes, Dans le cadre de cette étude, des participants à l'initiative de recherche sur les maladies neurodégénératives en Ontario ont été « génotypés » afin de déterminer si l’ApoE4 ou l’haplotype H1 mentionné ci-dessus peuvent être associés à cinq maladies neurodégénératives : 1) la maladie d’Alzheimer et d’autres troubles cognitifs légers ; 2) la sclérose latérale amyotrophique ; 3) la démence fronto-temporale ; 4) la maladie de Parkinson ; 5) et finalement les déficits cognitifs d’origine vasculaire. Méthodes : Pour chaque participant, la cartographie des génotypes a été établie en fonction de leur ApoE4 respectif et de la présence d’haplotypes H1 de la protéine tau associée aux microtubules. Des analyses de régression logistique ont été ensuite effectuées dans le but d’identifier de possibles liens avec ces maladies neurodégénératives. Résultats : Nos travaux ont confirmé l’association entre l’ApoE4 et une plus grande occurrence de cas d’Alzheimer, et ce, en tenant compte de l’effet d’une dose de médicament. Ils ont aussi montré une association entre la seule ApoE4 et des troubles cognitifs légers. Cela dit, il convient de préciser que les quatre autres maladies n’ont pas été associées à cet allèle. Plus encore, nous avons trouvé que l’allèle E2 de l’apolipoprotéine était associé à une occurrence plus faible de cas d’Alzheimer et de troubles cognitifs légers. Fait à souligner, aucune association n’a été détectée entre l’haplotype H1 de la protéine tau associée aux microtubules et nos cohortes atteintes de maladies neurodégénératives. Toutefois, à la suite du sous-typage de la cohorte de participants atteints de démence fronto-temporale, il s’est avéré que l’haplotype H1 était associé de façon notable à la paralysie supra-nucléaire progressive. Conclusion : Il s’agit de la première étude à analyser simultanément, au moyen de critères de participation cohérents et d’une analyse phénotypique élargie, les associations entre les isoformes de l’ApoE, l’haplotype H1 de la protéine tau associée aux microtubules et cinq maladies neurodégénératives.

Highlights • Cortical PET tau was compared between APOE4 carriers and non-carriers. • APOE4 carriers had higher cortical PET tau comparing to non-carriers. • APOE4 as a risk factor for tau accumulation in former contact sports athletes., Background Genetic polymorphisms like apolipoprotein E (APOE) and microtubule-associated protein tau (MAPT) genes increase the risk of neurodegeneration. Methods 38 former players (age 52.63±14.02) of contact sports underwent neuroimaging, biofluid collection, and comprehensive neuropsychological assessment. The [F-18]AV-1451 tracer signal was compared in the cortical grey matter between APOE4 allele carriers and non-carriers as well as carriers of MAPT H1H1 vs non-H1H1. Participants were then divided into the high (N = 13) and low (N = 13) groups based on cortical PET tau standard uptake value ratios (SUVRs) for comparison. Findings Cortical grey matter PET tau SUVR values were significantly higher in APOE4 carriers compared to non-carriers (p = 0.020). In contrast, there was no significant difference in SUVR between MAPT H1H1 vs non-H1H1 carrier genes (p = 1.00). There was a significantly higher APOE4 allele frequency in the high cortical grey matter PET tau group, comparing to low cortical grey matter PET tau group (p = 0.048). No significant difference in neuropsychological function was found between APOE4 allele carriers and non-carriers. Interpretation There is an association between higher cortical grey matter tau burden as seen with [F-18]AV-1451 PET tracer SUVR, and the APOE4 allele in former professional and semi-professional players at high risk of concussions. APOE4 allele may be a risk factor for tau accumulation in former contact sports athletes at high risk of neurodegeneration. Funding Toronto General and Western Hospital Foundations; Weston Brain Institute; Canadian Consortium on Neurodegeneration in ageing; Krembil Research Institute. There was no role of the funders in this study.

Age at onset of Alzheimer's disease is highly variable, and its modifiers (genetic or environmental) could act through epigenetic changes, such as DNA methylation at CpG sites. DNA methylation is also linked to ageing-the strongest Alzheimer's disease risk factor. DNA methylation age can be calculated using age-related CpGs and might reflect biological ageing. We conducted a clinical, genetic and epigenetic investigation of a unique Ashkenazi Jewish family with monozygotic triplets, two of whom developed Alzheimer's disease at ages 73 and 76, while the third at age 85 has no cognitive complaints or deficits in daily activities. One of their offspring developed Alzheimer's disease at age 50. Targeted sequencing of 80 genes associated with neurodegeneration revealed that the triplets and the affected offspring are heterozygous carriers of the risk APOE e4 allele, as well as rare substitutions in APP (p.S198P), NOTCH3 (p.H1235L) and SORL1 (p.W1563C). In addition, we catalogued 52 possibly damaging rare variants detected by NeuroX array in affected individuals. Analysis of family members on a genome-wide DNA methylation chip revealed that the DNA methylation age of the triplets was 6-10 years younger than chronological age, while it was 9 years older in the offspring with early-onset Alzheimer's disease, suggesting accelerated ageing.

Next-generation sequencing (NGS) is quickly revolutionizing how research into the genetic determinants of constitutional disease is performed. The technique is highly efficient with millions of sequencing reads being produced in a short time span and at relatively low cost. Specifically, targeted NGS is able to focus investigations to genomic regions of particular interest based on the disease of study. Not only does this further reduce costs and increase the speed of the process, but it lessens the computational burden that often accompanies NGS. Although targeted NGS is restricted to certain regions of the genome, preventing identification of potential novel loci of interest, it can be an excellent technique when faced with a phenotypically and genetically heterogeneous disease, for which there are previously known genetic associations. Because of the complex nature of the sequencing technique, it is important to closely adhere to protocols and methodologies in order to achieve sequencing reads of high coverage and quality. Further, once sequencing reads are obtained, a sophisticated bioinformatics workflow is utilized to accurately map reads to a reference genome, to call variants, and to ensure the variants pass quality metrics. Variants must also be annotated and curated based on their clinical significance, which can be standardized by applying the American College of Medical Genetics and Genomics Pathogenicity Guidelines. The methods presented herein will display the steps involved in generating and analyzing NGS data from a targeted sequencing panel, using the ONDRISeq neurodegenerative disease panel as a model, to identify variants that may be of clinical significance.

Objective To detect rare coding variants underlying loci detected by genome-wide association studies (GWAS) of late onset Alzheimer disease (LOAD). Methods We conducted targeted sequencing of ABCA7, BIN1, CD2AP, CLU, CR1, EPHA1, MS4A4A/MS4A6A, and PICALM in 3 independent LOAD cohorts: 176 patients from 124 Caribbean Hispanics families, 120 patients and 33 unaffected individuals from the 129 National Institute on Aging LOAD Family Study; and 263 unrelated Canadian individuals of European ancestry (210 sporadic patients and 53 controls). Rare coding variants found in at least 2 data sets were genotyped in independent groups of ancestry-matched controls. Additionally, the Exome Aggregation Consortium was used as a reference data set for population-based allele frequencies. Results Overall we detected a statistically significant 3.1-fold enrichment of the nonsynonymous mutations in the Caucasian LOAD cases compared with controls (p = 0.002) and no difference in synonymous variants. A stop-gain mutation in ABCA7 (E1679X) and missense mutation in CD2AP (K633R) were highly significant in Caucasian LOAD cases, and mutations in EPHA1 (P460L) and BIN1 (K358R) were significant in Caribbean Hispanic families with LOAD. The EPHA1 variant segregated completely in an extended Caribbean Hispanic family and was also nominally significant in the Caucasians. Additionally, BIN1 (K358R) segregated in 2 of the 6 Caribbean Hispanic families where the mutations were discovered. Interpretation Targeted sequencing of confirmed GWAS loci revealed an excess burden of deleterious coding mutations in LOAD, with the greatest burden observed in ABCA7 and BIN1. Identifying coding variants in LOAD will facilitate the creation of tractable models for investigation of disease-related mechanisms and potential therapies. Ann Neurol 2015;78:487–498

Amyotrophic lateral sclerosis (ALS) is characterised by a loss of motor neurons, leading to paralysis. Several autosomal dominant genes were implicated in ALS pathogenesis, such as SOD1 , with over 180 reported mutations (http://alsod.iop.kcl.ac.uk/), including a p.T137A substitution.1 ,2 Recently, ARHGEF28 , encoding an RNA binding protein involved in the aggregation of light neurofilaments in ALS, was suggested as a novel ALS gene (a heterozygous K280M>fs40X mutation was detected in three patients).3 ,4 Risk of ALS may be modulated by environmental factors, sex and ageing, which could be linked to epigenetic events (eg, DNA methylation). Monozygotic (MZ) twins provide the best opportunity to investigate environmental/epigenetic factors in disease development.5 Hence, we studied ALS-discordant MZ twins, including the evaluation of DNA methylation (DNAm) age, which is an accurate predictor of chronological age across different tissues.6 It is possible that DNAm age better reflects biological age than chronological age does, since age acceleration (DNAm age minus chronological age) was associated with several disorders and mortality. Participants were recruited from the ALS Clinic at the Sunnybrook Health Sciences Centre. Genetic and epigenetic analyses were conducted as described in the online supplementary methods, including mutation analysis of SOD1 and C9orf72 , NeuroX array, reverse transcription PCR (RT-PCR), whole genome DNA methylation array (HumanMethylation450 BeadChip) and bisulfite pyrosequencing. ### Supplementary data [jnnp-2016-313592supp.pdf] The MZ twins from a Canadian PED24 family of Italian origin were 52 years old at last examination and ALS-discordant for 17 years, with the second-born twin (9377) diagnosed with ALS at 35 years (figure 1 …

Objective Suggested C9orf72 disease mechanisms for amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration include C9orf72 haploinsufficiency, G4C2/C4G2 RNA foci, and dipeptide repeat (DPR) proteins translated from the G4C2 expansion; however, the role of small expansions (e.g., 30–90 repeats) is unknown and was investigated here. Methods We conducted a molecular and pathology study of a family in which the father (unaffected at age 90) carried a 70-repeat allele in blood DNA that expanded to ≈1,750 repeats in his children, causing ALS. Results Southern blotting revealed different degrees of mosaicism of small and large expansions in the father's tissues from the CNS. Surprisingly, in each mosaic tissue, C9orf72 mRNA levels were significantly increased compared to an ALS-affected daughter with a large expansion. Increased expression correlated with higher levels of the 70-repeat allele (the upregulation was also evident at the protein level). Remarkably, RNA foci and DPR burdens were similar or even significantly increased (in cerebellum) in the unaffected father compared to the daughter with ALS. However, the father did not display TDP-43 pathology and signs of neurodegeneration. Conclusion The presence of RNA foci and DPR pathology was insufficient for disease manifestation and TDP-43 pathology in the mosaic C9orf72 carrier with upregulated C9orf72 expression. It is important to conduct an investigation of similar cases, which could be found among unaffected parents of sporadic C9orf72 patients (e.g., 21% among Finnish patients with ALS). Caution should be taken when consulting carriers of small expansions because disease manifestation could be dependent on the extent of the somatic instability in disease-relevant tissues.

The G4C2 repeat expansion in C9orf72 is the most common known cause of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). We tested the hypothesis that the repeat expansion causes aberrant CpG methylation near the G4C2 repeat, which could be responsible for the downregulation of gene expression. We investigated the CpG methylation profile by two methods using genomic DNA from the blood of individuals with ALS (37 expansion carriers and 64 noncarriers), normal controls (n = 76), and family members of 7 ALS probands with the expansion. We report that hypermethylation of the CpG island 5′ of the G4C2 repeat is associated with the presence of the expansion (p < 0.0001). A higher degree of methylation was significantly correlated with a shorter disease duration (p < 0.01), associated with familial ALS (p = 0.009) and segregated with the expansion in 7 investigated families. Notably, we did not detect methylation for either normal or intermediate alleles (up to 43 repeats), bringing to question the current cutoff of 30 repeats for pathological alleles. Our study raises several important questions for the future investigation of large data sets, such as whether the degree of methylation corresponds to clinical presentation (ALS versus FTLD).

Traditional drug development for Alzheimer's disease (AD) is costly, time consuming and burdened by a very low success rate. An alternative strategy is drug repositioning, redirecting existing drugs for another disease. The large amount of biological data accumulated to date warrants a comprehensive investigation to better understand AD pathogenesis and facilitate the process of anti-AD drug repositioning. Hence, we generated a list of anti-AD protein targets by analyzing the most recent publically available 'omics' data, including genomics, epigenomics, proteomics and metabolomics data. The information related to AD pathogenesis was obtained from the OMIM and PubMed databases. Drug-target data was extracted from the DrugBank and Therapeutic Target Database. We generated a list of 524 AD-related proteins, 18 of which are targets for 75 existing drugs-novel candidates for repurposing as anti-AD treatments. We developed a ranking algorithm to prioritize the anti-AD targets, which revealed CD33 and MIF as the strongest candidates with seven existing drugs. We also found 7 drugs inhibiting a known anti-AD target (acetylcholinesterase) that may be repurposed for treating the cognitive symptoms of AD. The CAD protein and 8 proteins implicated by two 'omics' approaches (ABCA7, APOE, BIN1, PICALM, CELF1, INPP5D, SPON1, and SOD3) might also be promising targets for anti-AD drug development. Our systematic 'omics' mining suggested drugs with novel anti-AD indications, including drugs modulating the immune system or reducing neuroinflammation that are particularly promising for AD intervention. Furthermore, the list of 524 AD-related proteins could be useful not only as potential anti-AD targets but also considered for AD biomarker development.

Intermediate interrupted ataxin 2 (ATXN2) alleles (27-33 CAG-repeats) increase the risk for amyotrophic lateral sclerosis and are reported as modifiers in chromosome 9 open reading frame 72 (C9orf72) carriers, rendering susceptibility to amyotrophic lateral sclerosis rather than frontotemporal lobar degeneration. The clinical presentation of C9orf72 patients with pathogenic ATXN2 alleles (≥35 CAG-repeats) is unknown.Blood samples were collected from a family affected by ataxia, dementia, and parkinsonism, but not amyotrophic lateral sclerosis. Mutation analyses of the proband included C9orf72 and 14 ataxia genes, followed by segregation analyses in family members.Both affected siblings carry an uninterrupted 37-repeat expansion in ATXN2 and a methylated GThe CAG-expansion in ATXN2 likely caused the ataxia, whereas the dementia may be linked to both C9orf72 and ATXN2 repeat expansions. The pathological uninterrupted ATXN2 repeat may not have the same modifying effect as intermediate interrupted alleles. © 2016 International Parkinson and Movement Disorder Society.

Genome wide association studies have identified an association between Alzheimer’s disease (AD) and common polymorphisms in the MS4A and TREM loci (each containing a cluster of homologous genes) and should be thoroughly investigated for the presence of potentially functional variations. We conducted a mutation analysis by next generation sequencing of 15 genes within the MS4A and TREM gene clusters; and catalogued rare coding variants detected in a North American data set of 210 cases and 233 controls. Investigation of the 5 homologues genes in the TREM locus revealed potentially damaging rare variants in TREM2, TREML1, TREML2, and TREML4. In agreement with a previous report, we observed a significant enrichment of TREM2-damaging missense substitutions in cases (N 1⁄4 9; 4.2%) compared with controls (N1⁄42; 0.9%; p 1⁄4 0.010; after Yates’ correction p 1⁄4 0.022). Among known AD-associated TREM2 substitutions, we detected p.R47H, p.D87N, and p.H157Y affecting both TREM2 isoforms (NM_018965 and NM_001271821). In addition, we identified 2 cases with novel TREM2 variants (p.L205P and p.G219C), which mapped only to the isoform NM_001271821 at the C-terminus. Investigation of the MS4A gene cluster revealed that potentially damaging missense substitutions and loss-of-function variants were twice as frequent in controls (N 1⁄4 19; 8.2%) than cases (N 1⁄4 9; 4.3%), generating a nominally significant result (p 1⁄4 0.047; after Yates’ correction p 1⁄4 0.07). Validation of our observation in large data sets might address the question whether such variants could contribute to the protective effect of the minor alleles of Genome wide association study- significant single nucleotide polymorphisms at the MS4A locus.

Loss-of-function GRN mutations lead to GRN haploinsufficiency and consequently neurodegeneration with significant heterogeneity in clinical presentation of various syndromes. The aim of this study was to investigate the genetics and clinical features of patients with GRN-related frontotemporal lobar degeneration (FTLD) syndromes. We performed mutation analysis of GRN in 45 unrelated Canadian patients with a broad spectrum of FTLD-like syndromes (mean age at onset of 64.0 ± 11.2 years). In our cohort, two patients were carriers of two novel heterozygous alterations in GRN: 2 bp insertion (c.769–770insCC:p.Q257fs) and 12 bp deletion (c.1009–1020del:p.337–340del). Both patients presented with corticobasal syndrome supported by clinical and radiological findings. The absence of the mutant allele in the RT–PCR product was only observed for the sample with 2 bp insertion in GRN. In contrast, the allele with 12 bp deletion in GRN was not down-regulated at the RNA level and did not segregate with FTLD in the family. Our report extends the evidence for genetic and phenotypic variability in FTLD disorders and detects a novel pathogenic GRN mutation, carriers of which could eventually help to evaluate the efficacy of different treatments at early stages of dementia.

Importance Mutations in known causal Alzheimer disease (AD) genes account for only 1% to 3% of patients and almost all are dominantly inherited. Recessive inheritance of complex phenotypes can be linked to long (>1-megabase [Mb]) runs of homozygosity (ROHs) detectable by single-nucleotide polymorphism (SNP) arrays. Objective To evaluate the association between ROHs and AD in an African American population known to have a risk for AD up to 3 times higher than white individuals. Design, Setting, and Participants Case-control study of a large African American data set previously genotyped on different genome-wide SNP arrays conducted from December 2013 to January 2015. Global and locus-based ROH measurements were analyzed using raw or imputed genotype data. We studied the raw genotypes from 2 case-control subsets grouped based on SNP array: Alzheimer’s Disease Genetics Consortium data set (871 cases and 1620 control individuals) and Chicago Health and Aging Project–Indianapolis Ibadan Dementia Study data set (279 cases and 1367 control individuals). We then examined the entire data set using imputed genotypes from 1917 cases and 3858 control individuals. Main Outcomes and Measures The ROHs larger than 1 Mb, 2 Mb, or 3 Mb were investigated separately for global burden evaluation, consensus regions, and gene-based analyses. Results The African American cohort had a low degree of inbreeding ( F ~ 0.006). In the Alzheimer’s Disease Genetics Consortium data set, we detected a significantly higher proportion of cases with ROHs greater than 2 Mb ( P = .004) or greater than 3 Mb ( P = .02), as well as a significant 114-kilobase consensus region on chr4q31.3 (empirical P value 2 = .04; ROHs >2 Mb). In the Chicago Health and Aging Project–Indianapolis Ibadan Dementia Study data set, we identified a significant 202-kilobase consensus region on Chr15q24.1 (empirical P value 2 = .02; ROHs >1 Mb) and a cluster of 13 significant genes on Chr3p21.31 (empirical P value 2 = .03; ROHs >3 Mb). A total of 43 of 49 nominally significant genes common for both data sets also mapped to Chr3p21.31. Analyses of imputed SNP data from the entire data set confirmed the association of AD with global ROH measurements (12.38 ROHs >1 Mb in cases vs 12.11 in controls; 2.986 Mb average size of ROHs >2 Mb in cases vs 2.889 Mb in controls; and 22% of cases with ROHs >3 Mb vs 19% of controls) and a gene-cluster on Chr3p21.31 (empirical P value 2 = .006-.04; ROHs >3 Mb). Also, we detected a significant association between AD and CLDN17 (empirical P value 2 = .01; ROHs >1 Mb), encoding a protein from the Claudin family, members of which were previously suggested as AD biomarkers. Conclusions and Relevance To our knowledge, we discovered the first evidence of increased burden of ROHs among patients with AD from an outbred African American population, which could reflect either the cumulative effect of multiple ROHs to AD or the contribution of specific loci harboring recessive mutations and risk haplotypes in a subset of patients. Sequencing is required to uncover AD variants in these individuals.

Corticobasal syndrome (CBS) is a neurodegenerative disease characterized by progressive asymmetrical rigidity and apraxia, cortical sensory loss, myoclonus, dystonia, and cognitive impairment. CBS is usually sporadic and associated with tau pathology but there are reports of TDP-43 pathology. We screened 39 CBS cases to determine if any of the cases could be explained by a G4C2-repeat expansion in a noncoding region of C9orf72 gene, the most common genetic cause of frontotemporal lobar degeneration and amyotrophic lateral sclerosis. One patient with CBS had a large (>50 repeats) expansion in C9orf72. Our case features a 63-year-old right-handed woman who developed mild apathy 9 years before presentation, which progressed to include behavioral symptoms, oral stereotypies, significant language impairment, parkinsonism and apraxia. A magnetic resonance imaging acquired at age 60 years, that is, 6 years after disease onset revealed significant asymmetric left > right frontotemporal atrophy, including orbitofrontal and parietal areas. Her father developed a behavioral syndrome and died at an early age. This case highlights the importance of genetic screening for C9orf72 in patients with CBS.

The first mutations described in PINK1 were homozygous. More recently, heterozygous mutations have been reported but the role of heterozygosity in disease pathogenesis is still debated. We describe two unrelated cases with PINK1 mutations (homozygous nonsense and heterozygous missense) that highlight issues regarding the role of heterozygous mutations and the utility of genetic screening in patient care. © 2006 Movement Disorder Society

Recent studies have demonstrated that cholesterol metabolism has an important role in Alzheimer's disease (AD) pathogenesis, suggesting that cholesterol-related genes may be significant genetic risk factors for AD. Based on the results of genome-wide screens, along with biological studies, we selected three genes as candidates for AD risk factors: ATP-binding cassette transporter A1 (ABCA1), cholesterol 25-hydroxylase (CH25H) and cholesterol 24-hydroxylase (CH24H). Case–control of North American Caucasians and AD families of Caribbean Hispanic origin were examined. Although excellent biological candidates, the case–control dataset did not support the hypothesis that these three genes were associated with susceptibility to AD. Similarly, no association was found in the Caribbean Hispanic families for CH25H. However, we did observe a possible interaction between ABCA1 and APOE in the Hispanics.

Background: In addition to the four well-confirmed genes linked to early-onset Parkinson disease (PD) (SNCA, PARKIN, DJ-1, and PINK1), mutations in the leucine-rich repeat kinase 2 gene (LRRK2) have recently been identified in families with autosomal dominant late-onset PD. Objective: To perform mutation analysis of LRRK2 in probands of families showing dominant inheritance of PD and to conduct a case control association study to test the hypothesis that common coding variations might be associated with increased susceptibility to PD. Methods: All 51 LRRK2 coding exons were sequenced in 23 probands and the mutation frequencies were evaluated in 180 neurologically normal control subjects. For the association study the authors genotyped four coding LRRK2 polymorphisms in 250 normal control subjects and 121 patients with PD (predominantly white patients of Canadian origin), 84% of whom had age at onset before 50 years and 42% had a positive family history. Results: The authors identified three probands with heterozygous LRRK2 mutations: two of them have the known G2019S substitution and one proband has a novel I1371V substitution. Mutation analysis of a large family demonstrated complete segregation of the G2019S with PD. However, there was no association between PD and any of the four polymorphisms at the allelic or genotypic levels (p > 0.17). Furthermore, the authors did not detect a modifying effect for any genotype or of APOE genotypes upon the age at onset in the PD group (p > 0.20). Conclusions: The results support the prior suggestion that LRRK2 mutations cause PD. The disease in the families reported here presents a phenotype indistinguishable from typical PD. All three families demonstrate a very variable age at onset that is not explained by APOE genotypes. The common coding variations in the LRRK2 gene neither constitute strong PD risk factors nor modify the age at onset; however, the possibility of a modest risk effect remains to be assessed in large datasets.

Parkinson's disease (PD) is the most common neurodegenerative movement disorder with a substantial genetic component (which is more pronounced in earlier onset cases). In addition to three well-confirmed PD genes (SNCA, parkin and DJ-1), mutations in the PTEN Induced Kinase (PINK1) gene have recently been identified in families with recessive early onset PD. We tested the hypothesis that three common coding variations (Leu63Leu, Ala340Thr and Asn521Thr) could increase the risk of PD. We performed a case control association study in a series of 91 PD cases (Caucasian of Canadian origin) and 182 normal controls. The patients were largely pre-selected for having an early age of onset (50 years) and/or a positive family history. Our results did not reveal any evidence of association between PD and any of the three SNPs at the allelic or genotypic levels (p0.25). Furthermore, we did not detect a modifying effect for any genotype upon the age of onset in the PD group (p0.19). Nevertheless, it remains to be evaluated whether PINK1 variations contribute to the risk of common late onset sporadic PD.

The most common cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) is a G4C2-repeat expansion in C9orf72. However, the lower limit for pathological repeats has not been established and expansions with different sizes could have different pathological consequences. One of the implicated disease mechanisms is haploinsufficiency. Previously, we identified expansion-specific hypermethylation at the 5´ CpG-island near the G4C2-repeat, but only in a fraction of carriers (up to 36 %). Here, we tested the hypothesis that the G4C2-repeat itself could be the main site of methylation. To evaluate (G4C2) n -methylation, we developed a novel assay, which was validated by an independent methylation-sensitive restriction enzyme assay. Notably, both assays are qualitative but not quantitative. Blood DNA was available for 270 unrelated individuals, including 71 expansion carriers. In addition, we investigated blood DNA from family members of 16 probands, and 38 DNA samples from multiple tissues of 10 expansion carriers. Finally, we tested DNA from different tissues of an ALS patient carrying a somatically unstable 90-repeat. We demonstrated that the G4C2-expansion is generally methylated in unrelated carriers of alleles >50 repeats (97 %), while small (

Genetic analyses of patients with neurodegenerative disorders have identified multiple genes that need to be investigated for the presence of damaging variants. However, mutation analysis by Sanger sequencing is costly and time consuming. We tested the utility of a recently designed semi-custom genome-wide array (NeuroX; Illumina, Inc) tailored to study neurodegenerative diseases (e.g., mutation screening). We investigated 192 patients with 4 different neurodegenerative disorders for the presence of rare damaging variations in 77 genes implicated in these diseases. Several causative mutations were identified and confirmed by Sanger sequencing, including PSEN1 p.M233T responsible for Alzheimer's disease in a large Italian family, as well as SOD1 p.A4V and p.I113T in patients with amyotrophic lateral sclerosis. In total, we identified 78 potentially damaging rare variants (frequency

The G₄C₂-repeat expansion in C9orf72 is a common cause of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). C9orf72 transcription is reduced in expansion carriers implicating haploinsufficiency as one of the disease mechanisms. Indeed, our recent ALS study revealed that the expansion was associated with hypermethylation of the CpG-island (5'of the repeat) in DNA samples obtained from different tissues (blood, brain and spinal cord). However, the link between FTLD and methylation of the CpG-island is unknown. Hence, we investigated the methylation profile of the same CpG-island by bisulfite sequencing of DNA obtained from blood of 34 FTLD expansion carriers, 166 FTLD non-carriers and 103 controls. Methylation level was significantly higher in FTLD expansion carriers than non-carriers (P = 7.8E-13). Our results were confirmed by two methods (HhaI-assay and sequencing of cloned bisulfite PCR products). Hypermethylation occurred only in carriers of an allele with50 repeats, and was not detected in non-carriers or individuals with an intermediate allele (22-43 repeats). As expected, the position/number of methylated CpGs was concordant between the sense and anti-sense DNA strand, suggesting that it is a stable epigenetic modification. Analysis of the combined ALS and FTLD datasets (82 expansion carriers) revealed that the degree of methylation of the entire CpG-island or contribution of specific CpGs (n = 26) is similar in both syndromes, with a trend towards a higher proportion of ALS patients with a high methylation level (P = 0.09). In conclusion, we demonstrated that hypermethylation of the CpG-island 5'of the G₄C₂-repeat is expansion-specific, but not syndrome-specific (ALS versus FTLD).

Amyloid beta-peptide (Abeta) plays a central role in the pathogenesis of Alzheimer's disease (AD). The gene encoding the beta-site APP cleaving enzyme (BACE), one of two enzymes that sequentially cleave the beta-amyloid precursor protein to generate Abeta, has recently been cloned. We tested the hypothesis that BACE might be genetically associated with AD by linkage analysis (56 pedigrees), by direct nucleotide sequencing of the entire open reading frame (20 subjects with familial AD, and 10 subjects with sporadic AD) and by allelic association analysis (155 AD cases and 173 non-demented controls). Our results revealed no evidence for either genetic linkage or allelic association between BACE and AD, and no coding sequence mutations were detected in the open reading frame of the BACE gene. These data suggest that while BACE protein plays an important role in the pathogenesis of AD, and may be a robust therapeutic target, it is unlikely to be a major AD susceptibility locus.

The presenilins and nicastrin, a type 1 transmembrane glycoprotein, form high molecular weight complexes that are involved in cleaving the beta-amyloid precursor protein (betaAPP) and Notch in their transmembrane domains. The former process (termed gamma-secretase cleavage) generates amyloid beta-peptide (Abeta), which is involved in the pathogenesis of Alzheimer's disease. The latter process (termed S3-site cleavage) generates Notch intracellular domain (NICD), which is involved in intercellular signalling. Nicastrin binds both full-length betaAPP and the substrates of gamma-secretase (C99- and C83-betaAPP fragments), and modulates the activity of gamma-secretase. Although absence of the Caenorhabditis elegans nicastrin homologue (aph-2) is known to cause an embryonic-lethal glp-1 phenotype, the role of nicastrin in this process has not been explored. Here we report that nicastrin binds to membrane-tethered forms of Notch (substrates for S3-site cleavage of Notch), and that, although mutations in the conserved 312-369 domain of nicastrin strongly modulate gamma-secretase, they only weakly modulate the S3-site cleavage of Notch. Thus, nicastrin has a similar role in processing Notch and betaAPP, but the 312-369 domain may have differential effects on these activities. In addition, we report that the Notch and betaAPP pathways do not significantly compete with each other.

Recently, several CHCHD2 mutations were reported to be associated with autosomal dominant Parkinson's disease (PD) in a Japanese population. However, an association between CHCHD2 and PD was not observed in 2 Caucasian data sets. The present study searched for CHCHD2 coding variants in Canadian PD patients. Sanger sequencing of all CHCHD2 exons revealed no coding mutations in 155 familial cases. Moreover, 3 coding CHCHD2 polymorphisms available on the NeuroX array (Pro2Leu, Pro14Ser, and Ile118Met) were homozygous for the major allele in an additional 85 PD patients. Our study suggests that CHCHD2 mutations may not account for PD in Canadian patients.

PS1 mutations are associated with classic Alzheimer's disease (AD); however, some families develop AD and spastic paraplegia (SP) with brain pathology characterized by Abeta cotton wool plaques. The authors report a variant AD family with the E280Q PS1 mutation. The fact that the same PS1 mutation can be found in patients with either variant or classic AD argues in favor of the presence of a genetic modifier. The authors have excluded that this modifier effect originates from coding sequence variations in three SP genes or from a second mutation in the other AD genes.

CR1 is a novel Alzheimer's disease (AD) gene identified by genome-wide association studies (GWAS). Recently, we showed that AD risk could be explained by an 18-kilobase insertion responsible for the complement component (3b/4b) receptor 1 (CR1)-S isoform. We investigated the relevance of the CR1 isoforms to AD in a Canadian dataset. Also, we genotyped rs4844610 tagging the GWAS-significant CR1 single nucleotide polymorphisms. Individuals with F/S genotype had a 1.8 times increased risk for AD compared with F/F genotype (p-adjusted = 0.003), while rs4844610 was only marginally significant (p-adjusted = 0.024). The analyses of brain samples demonstrated that the CR1-S isoform is expressed at lower protein levels than CR1-F (p < 0.0001) hence likely associated with increased complement activation. Intriguingly, our neuropathological results show that the pattern of CR1 expression in neurons is different between the F/F and F/S genotypes (filiform vs. vesicular-like profiles). Furthermore, double labeling studies supported a differential distribution of CR1 in neurons (endoplasmic reticulum intermediate compartment vs. lysosomes). These observations indicate that the CR1-S and CR1-F isoforms could be processed in different ways in neurons. In conclusion, our results support that the CR1-S isoform explains the GWAS signals and open a novel prospect for the investigation of CR1-related disease mechanisms.

The objectives of this study were to estimate frontotemporal dementia (FTD) prevalence, identify FTD-related mutations, and correlate FTD phenotype with mutations in a Southern Italian population. The study population consisted of subjects ≥ 50 years of age residing in the Community of Biv. on January 1, 2004, and a door-to-door 2-phase design was used. Genetic and biochemical analyses were done on samples collected from 32 patients. Prevalence rates were 0.6 for Alzheimer's disease, 0.4 for vascular dementia (VD), 3.5 for FTD, 0.2 for Parkinson dementia, and 1.2 for unspecified dementia. Three GRN (1 known and 2 novel) mutations with reduced plasma protein levels were found associated to 3 distinct phenotypes (behavioral, affective, and delirious type). We report an unusually high FTD prevalence in the investigated population, but a low prevalence of Alzheimer's disease. We confirm the heterogeneity of FTD phenotype associated with different GRN mutations.

It has been shown that mutations in the Fused in Sarcoma gene (FUS) could explain up to 5% of cases with familial amyotrophic lateral sclerosis (ALS). Our mutation analysis of FUS in a Canadian ALS patient of Chinese origin revealed an unusual novel heterozygous double point mutation (R514S/E516V) confirming that exon 15 is a mutation hot-spot. The substitutions are in cis position to each other and affect highly conserved codons in the RGG-rich region of the FUS protein. The absence of clinical signs of ALS in the relatives of the affected carrier could indicate that this mutation is incompletely penetrant or de novo. The pathologic significance of the R514S/E516V mutation was confirmed by immunohistochemistry. FUS-positive cytoplasmic inclusions were noted in a moderate number in neurons and abundantly in glial cells in the motor cortex and the brainstem. Of interest, a significant number of neuronal and glial FUS-positive inclusions were found in the tegmentum of the brainstem. Importantly, some neurons with inclusions showed retention of the normal nuclear FUS immunostaining.

Background: About 20% of familial amyotrophic lateral sclerosis (ALS) is caused by mutations in SOD1 and is typically transmitted as an autosomal dominant trait. However, due to reduced mutation penetrance, the disease may present in a recessive or sporadic manner. Objective: To determine the factors responsible for the low penetrance of the SOD1 mutation. Methods: Twelve members of a Canadian ALS family of Filipino origin were recruited for the study. SOD1 was sequenced in the proband. SOD1 expression was assessed by real-time-PCR and immunoblotting. Results: The proband was a homozygous carrier of a novel 6 bp deletion in exon 2 (ΔG27/P28), the pathologic significance of which was confirmed by immunohistochemistry. Eight living family members are heterozygotes and remain unaffected at ages ranging between 48 and 85 years. Haplotype analysis showed that the deletion is a single founder mutation likely common in the Cagayan province (Philippines). The low penetrance of the mutation is explained by the fact that it enhances the naturally occurring alternative splicing of exon 2 of the SOD1 mRNA, leading to reduced transcription of the mutant allele. Indeed, Western blot analysis demonstrated the low level of SOD1 protein in carriers of the ΔG27/P28 compared to wild-type individuals or a carrier of the A4V SOD1 mutation. Conclusion: The enhanced splicing of exon 2 acts as a natural knock-down of the mutant SOD1 allele in the Filipino amyotrophic lateral sclerosis (ALS) family. There is a need for careful investigation of splicing isoforms of SOD1 and other ALS genes as factors influencing the severity of disease.

Here we report the relationship between age at onset, clinical course and genotype in a family with combined LRRK2 G2019S and Parkin exon 2 deletions. In the combined mutation carriers the age at onset and clinical course was highly variable and not always younger than in the carriers of LRRK2 G2019S mutations alone.

Background: Frontotemporal dementia (FTD) in several 17q21-linked families was recently explained by truncating mutations in the progranulin gene ( GRN ). Objective: To determine the frequency of GRN mutations in a cohort of Caucasian patients with FTD without mutations in known FTD genes. Methods: GRN was sequenced in a series of 78 independent FTD patients including 23 familial subjects. A different Calabrian dataset (109 normal control subjects and 96 FTD patients) was used to establish the frequency of the GRN mutation. Results: A novel truncating GRN mutation (c.1145insA) was detected in a proband of an extended consanguineous Calabrian kindred. Segregation analysis of 70 family members revealed 19 heterozygous mutation carriers including 9 patients affected by FTD. The absence of homozygous carriers in a highly consanguineous kindred may indicate that the loss of both GRN alleles might lead to embryonic lethality. An extremely variable age at onset in the mutation carriers (more than five decades apart) is not explained by APOE genotypes or the H1/H2 MAPT haplotypes. Intriguingly, the mutation was excluded in four FTD patients belonging to branches with an autosomal dominant mode of inheritance of FTD, suggesting that another novel FTD gene accounts for the disease in the phenocopies. It is difficult to clinically distinguish phenocopies from GRN mutation carriers, except that language in mutation carriers was more severely compromised. Conclusion: The current results imply further genetic heterogeneity of frontotemporal dementia, as we detected only one GRN -linked family (about 1%). The value of discovering large kindred includes the possibility of a longitudinal study of GRN mutation carriers.

A recent study by Bannwarth et al. (2014) implicated CHCHD10 as a novel gene for amyotrophic lateral sclerosis/frontotemporal lobar degeneration (ALS/FTLD), reporting a p.S59L substitution (c.176C > T; NM_213720.2) in a large French kindred. Affected family members were presented with a complex phenotype that included symptoms of amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), cerebellar ataxia, Parkinson's disease and a mitochondrial myopathy associated with multiple mitochondrial DNA deletions. So far, seven missense CHCHD10 mutations have been reported in patients with a broad phenotypic range, including ALS/FTLD (p.S59L and p.P34S) (Bannwarth et al., 2014; Chaussenot et al., 2014), ALS (p.R15L and p.G66V) (Johnson et al., 2014; Muller et al., 2014), myopathy (p.R15S and p.G58R) (Ajroud-Driss et al., 2015) and late-onset spinal motor neuronopathy (p.G66V) (Penttila et al., 2015). All of them affect exon 2 (a mutational hotspot of CHCHD10). Fil: Zhang, Ming. University of Toronto; Canadá Fil: Xi, Zhengrui. University of Toronto; Canadá Fil: Zinman, Lorne. Sunnybrook Health Sciences Centre; Estados Unidos Fil: Bruni, Amalia C.. Lamezia Terme. Regional Neurogenetic Centre; Italia Fil: Maletta, Raffaele G.. Lamezia Terme. Regional Neurogenetic Centre; Italia Fil: Curcio, Sabrina A. M.. Lamezia Terme. Regional Neurogenetic Centre; Italia Fil: Rainero, Innocenzo. Università di Torino; Italia Fil: Rubino, Elisa. Università di Torino; Italia Fil: Pinessi, Lorenzo. Università di Torino; Italia Fil: Nacmias, Benedetta. Universita Degli Studi Di Firenze; Italia Fil: Sorbi, Sandro. Universita Degli Studi Di Firenze; Italia Fil: Galimberti, Daniela. Università degli Studi di Milano; Italia Fil: Lang, Anthony E.. Toronto Western Hospital University Of Toronto; Canadá. University of Toronto; Canadá Fil: Fox, Susan. Toronto Western Hospital University Of Toronto; Canadá. University of Toronto; Canadá Fil: Surace, Ezequiel Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina Fil: Ghani, Mahdi. University of Toronto; Canadá Fil: Guo, Jing. University of Toronto; Canadá Fil: Sato, Christine. University of Toronto; Canadá Fil: Moreno, Danielle. University of Toronto; Canadá Fil: Liang, Yan. University of Toronto; Canadá Fil: Keith, Julia. Sunnybrook Health Sciences Centre; Canadá Fil: Traynor, Bryan J.. National Institute on Aging. Laboratory of Neurogenetics. Neuromuscular Diseases Research Section; Estados Unidos Fil: George-Hyslop, Peter St.. University of Toronto; Canadá. University of Cambridge; Reino Unido Fil: Rogaeva, Ekaterina. University of Toronto; Canadá

There is increasing evidence of a clinical, neuropathological and genetic overlap between frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). We conducted a case–control study using a UK dataset to test the hypothesis that polymorphisms in two FTD-related genes (GRN and FT74) are associated with increased susceptibility to ALS. We evaluated the majority of known genetic variability in IFT74 and GRN. The results revealed that the common variations in IFT74 and GRN neither constitute strong ALS risk factors nor modify the age-at-onset. However, the possibility of a modest risk effect remains to be assessed in large datasets.

Background To date, 5 well-confirmed genes for Parkinson disease (PD) have been identified, including 3 autosomal recessive genes: PTEN-induced putative kinase 1 ( PINK1 ), parkin , and DJ-1 . Almost nothing is known about the genetics of PD in Saudi Arabia; however, consanguineous families, not infrequent in this population, could be important in the evaluation of known PD genes and the search for new PD factors in the future. Objective To investigate known recessive PD genes in 5 consanguineous Saudi families with PD. Design The entire open frame as well as the untranslated region and all 5′ and 3′ intron-exon boundaries of the PINK1 , parkin, and DJ-1 genes were sequenced in 5 probands in Saudi families. Results Four of 5 probands tested negative for PINK1 , parkin , and DJ-1 mutations. However, in a large Saudi family with PD with at least 3 consanguineous marriages between first cousins, we detected a threonine to methionine substitution at codon 313 (T313M) PINK1 mutation that affected the kinase domain. Manifestations of the disease in this family included early onset (age, 28-38 years), tremulous movement, slow progression, diurnal fluctuations, bradykinesia, good response to levodopa therapy, and only mild dyskinesias. A neurologist blinded to genetic status clinically evaluated 15 family members, all older than 20 years, and diagnosed PD only in individuals who were later found to be homozygous for the T313M mutation. None of the 13 heterozygotes demonstrated any sign of PD. Conclusion A homozygous T313M mutation is responsible for PD in this large Saudi family. However, the heterozygous T313M mutation does not act as a PD susceptibility factor, which is in contrast to several reports of mutations affecting only 1 PINK1 allele discovered in sporadic PD.

We describe a Japanese family in which inheritance of a novel mutation p.A100T in SPG6 resulted in an autosomal dominant form of hereditary spastic paraplegia (ADHSP). Clinical investigation showed a pure form of HSP. Our study demonstrates further allelic heterogeneity of SPG6.

A nonsense/protein chain-terminating mutation in the CHMP2B gene has recently been reported as a cause of frontotemporal dementia (FTD) in the single large family known to show linkage to chromosome 3. Screening for mutations in this gene in a large series of FTD families and individual patients led to the identification of a protein-truncating mutation in 2 unaffected members of an Afrikaner family with FTD, but not in their affected relatives. The putative pathogenicity of CHMP2B mutations for dementia is discussed.

We describe a Brazilian family in which inheritance of a G106R mutation in the SPG6 gene (also know as NIPA1) resulted in an autosomal dominant form of hereditary spastic paraplegia (ADHSP). Clinical investigations indicated that this family has a pure form of spastic paraplegia. All patients presented with gait difficulty in their twenties, progressing to frank spastic paraplegia during the next decade. Our report further supports evidence that mutations in SPG6 cause ADHSP.

The plasmin system is involved in the degradation of Abeta peptides, the accumulation of which in brain is a hallmark of Alzheimer's disease (AD). In a North European case-control AD dataset we studied 14 common variations in the PLG, PAI-1, PLAT and PLI genes encoding components of the plasmin system. Among the four polymorphisms in the PLAT, PAI-1 and PLI genes showing nominally significant evidence for an association with AD (allele p-value=0.01-0.00003) the strongest association was detected for the deletion allele in the Alu-repeat region of the PLAT gene. However, none of these positive results were confirmed in follow-up studies using an independent Canadian case-control cohort and two familial AD datasets of North European and Caribbean Hispanic origin. Thus, the current survey does not support the notion that common polymorphisms in the plasmin genes influence the development of AD.

We describe a novel Leu174Arg PS1 mutation in two members of a Bavarian family which were initially diagnosed with frontotemporal dementia. Intriguingly, there is the possibility that there is an 18th century founder effect and that this family is related to original kindreds with familial Alzheimer disease described in the early 20th century.

Parkinson's disease (PD) is a common progressive neurodegenerative disorder characterized clinically by a combination of motor symptoms. Identifying novel PD genetic risk factors is important for understanding its pathogenesis. A recent study suggested that up to 21% of subjects with PD may have mutations in the glucocerebrosidase (GBA) gene. We investigated the GBA gene for mutations in 88 PD cases and 122 normal controls and detected the presence of heterozygous GBA mutations in 5 PD cases and in 1 control. Sequencing of the entire open reading frame of the GBA gene in a subset of 25 cases with early-onset PD (