Diego. ADNI data are disseminated by the Laboratory for Neuro Imaging at the University of Southern California. We thank Drs. D. Stephen Snyder and Marilyn Miller from NIA who are ex-officio ADGC members. EADI. This work has been developed and supported by the LABEX (laboratory of excellence program investment for the future) DISTALZ grant (Development of Innovative Strategies for a Transdisciplinary approach to ALZheimer's disease) including funding from MEL (Metropole européenne de Lille), ERDF (European Regional Development Fund) and Conseil Régional Rotterdam, Netherlands Organization for the Health Research and Development (ZonMw), the Research Institute for Diseases in the Elderly (RIDE), the Ministry of Education, Culture and Science, the Ministry for Health, Welfare and Sports, the European Commission (DG XII), and the Municipality of Rotterdam. The authors are grateful to the study participants, the staff from the Rotterdam Study and the participating general practitioners and pharmacists. The generation and management of GWAS genotype data for the Rotterdam Study (RS-I, RS-II, RS-III) was executed by the Human Genotyping Facility of the Genetic Laboratory of the

The Alzheimer Disease Genetics Consortium (ADGC) performed a genome-wide association study (GWAS) of late-onset Alzheimer disease (LOAD) using a 3 stage design consisting of a discovery stage (Stage 1) and two replication stages (Stages 2 and 3). Both joint and meta-analysis analysis approaches were used. We obtained genome-wide significant results at MS4A4A [rs4938933; Stages 1+2, meta-analysis (PM) = 1.7 × 10−9, joint analysis (PJ) = 1.7 × 10−9; Stages 1–3, PM = 8.2 × 10−12], CD2AP (rs9349407; Stages 1–3, PM = 8.6 × 10−9), EPHA1 (rs11767557; Stages 1–3 PM = 6.0 × 10−10), and CD33 (rs3865444; Stages 1–3, PM = 1.6 × 10−9). We confirmed that CR1 (rs6701713; PM = 4.6×10−10, PJ = 5.2×10−11), CLU (rs1532278; PM = 8.3 × 10−8, PJ = 1.9×10−8), BIN1 (rs7561528; PM = 4.0×10−14; PJ = 5.2×10−14), and PICALM (rs561655; PM = 7.0 × 10−11, PJ = 1.0×10−10) but not EXOC3L2 are LOAD risk loci1–3.

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We recommend a new term, “primary age-related tauopathy” (PART), to describe a pathology that is commonly observed in the brains of aged individuals. Many autopsy studies have reported brains with neurofibrillary tangles (NFT) that are indistinguishable from those of Alzheimer's disease (AD), in the absence of amyloid (Aβ) plaques. For these “NFT+/Aβ−” brains, for which formal criteria for AD neuropathologic changes are not met, the NFT are mostly restricted to structures in the medial temporal lobe, basal forebrain, brainstem, and olfactory areas (bulb and cortex). Symptoms in persons with PART usually range from normal to amnestic cognitive changes, with only a minority exhibiting profound impairment. Because cognitive impairment is often mild, existing clinicopathologic designations, such as “tangle-only dementia” and “tangle-predominant senile dementia”, are imprecise and not appropriate for most subjects. PART is almost universally detectable at autopsy among elderly individuals, yet this pathological process cannot be specifically identified pre-mortem at the present time. Improved biomarkers and tau imaging may enable diagnosis of PART in clinical settings in the future. Indeed, recent studies have identified a common biomarker profile consisting of temporal lobe atrophy and tauopathy without evidence of Aβ accumulation. For both researchers and clinicians, a revised nomenclature will raise awareness of this extremely common pathologic change while providing a conceptual foundation for future studies. Prior reports that have elucidated features of the pathologic entity we refer to as PART are discussed, and working neuropathological diagnostic criteria are proposed.

Summary A hexanucleotide repeat expansion (HRE), (GGGGCC)n, in C9orf72 is the most common genetic cause of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here we identify a molecular mechanism by which structural polymorphism of the HRE leads to ALS/FTD pathology and defects. The HRE forms DNA and RNA G-quadruplexes with distinct structures and promotes RNA•DNA hybrids (R-loops). The structural polymorphism causes a repeat length-dependent accumulation of transcripts aborted in the HRE region. These transcribed repeats bind to ribonucleoproteins in a conformationdependent manner. Specifically, nucleolin (NCL), an essential nucleolar protein, preferentially binds the HRE G-quadruplex, and patient cells show evidence of nucleolar stress. Our results demonstrate that distinct C9orf72 HRE structural polymorphism at both DNA and RNA levels initiates molecular cascades leading to ALS/FTD pathologies, and provide the basis for a mechanistic model for repeat-associated neurodegenerative diseases.

The finding that a GGGGCC (G 4 C 2 ) hexanucleotide repeat expansion in the chromosome 9 ORF 72 (C9ORF72) gene is a common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) links ALS/FTD to a large group of unstable microsatellite diseases. Previously, we showed that microsatellite expansion mutations can be bidirectionally transcribed and that these mutations express unexpected proteins by a unique mechanism, repeat-associated non-ATG (RAN) translation. In this study, we show that C9ORF72 antisense transcripts are elevated in the brains of C9ORF72 expansion-positive [C9(+)] patients, and antisense GGCCCC (G 2 C 4 ) repeat-expansion RNAs accumulate in nuclear foci in brain. Additionally, sense and antisense foci accumulate in blood and are potential biomarkers of the disease. Furthermore, we show that RAN translation occurs from both sense and antisense expansion transcripts, resulting in the expression of six RAN proteins (antisense: Pro-Arg, Pro-Ala, Gly-Pro; and sense: Gly-Ala, Gly-Arg, Gly-Pro). These proteins accumulate in cytoplasmic aggregates in affected brain regions, including the frontal and motor cortex, hippocampus, and spinal cord neurons, with some brain regions showing dramatic RAN protein accumulation and clustering. The finding that unique antisense G 2 C 4 RNA foci and three unique antisense RAN proteins accumulate in patient tissues indicates that bidirectional transcription of expanded alleles is a fundamental pathologic feature of C9ORF72 ALS/FTD. Additionally, these findings suggest the need to test therapeutic strategies that target both sense and antisense RNAs and RAN proteins in C9ORF72 ALS/FTD, and to more broadly consider the role of antisense expression and RAN translation across microsatellite expansion diseases.cytoplasmic inclusions | clustered aggregates | noncoding RNA T he chromosome 9p21-linked form of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), the most common cause of familial FTD and ALS identified to date, is caused by an expanded GGGGCC (G 4 C 2 ) hexanucleotide repeat in intron 1 of chromosome 9 ORF 72 (C9ORF72) (1, 2). The C9ORF72 mutation is found in 40% of familial and 7% of sporadic ALS cases and 21% of familial and 5% of sporadic FTD patients (3). The discovery of the C9ORF72 expansion has generated substantial excitement because it connects ALS and FTD to a large group of disorders caused by microsatellite expansion mutations (4).Traditionally, microsatellite expansion mutations located in predicted coding and noncoding regions were thought to cause disease by protein gain-or loss-of-function or RNA gain-of-function mechanisms (4). Protein loss-of-function has been proposed to underlie C9ORF72-driven ALS/FTD because the expansion mutation leads to decreased levels of variant 1 transcripts and potential decreases in C9ORF72 protein expression (1, 5). Additionally, because the C9ORF72 G 4 C 2 expansion mutation is located in an intron, several studies have pursued the hypothesis that C9-linked ALS/FTD results f...

The highly complex structure of the human brain is strongly shaped by genetic influences1. Subcortical brain regions form circuits with cortical areas to coordinate movement2, learning, memory3 and motivation4, and altered circuits can lead to abnormal behaviour and disease2. To investigate how common genetic variants affect the structure of these brain regions, here we conduct genome-wide association studies of the volumes of seven subcortical regions and the intracranial volume derived from magnetic resonance images of 30,717 individuals from 50 cohorts. We identify five novel genetic variants influencing the volumes of the putamen and caudate nucleus. We also find stronger evidence for three loci with previously established influences on hippocampal volume5 and intracranial volume6. These variants show specific volumetric effects on brain structures rather than global effects across structures. The strongest effects were found for the putamen, where a novel intergenic locus with replicable influence on volume (rs945270; P = 1.08 × 10−33; 0.52% variance explained) showed evidence of altering the expression of the KTN1 gene in both brain and blood tissue. Variants influencing putamen volume clustered near developmental genes that regulate apoptosis, axon guidance and vesicle transport. Identification of these genetic variants provides insight into the causes of variability inhuman brain development, and may help to determine mechanisms of neuropsychiatric dysfunction.

Alzheimer's disease (AD) is an age-related disorder characterized by deposition of amyloid ␤-peptide (A␤) and degeneration of neurons in brain regions such as the hippocampus, resulting in progressive cognitive dysfunction. The pathogenesis of AD is tightly linked to A␤ deposition and oxidative stress, but it remains unclear as to how these factors result in neuronal dysfunction and death. We report alterations in sphingolipid and cholesterol metabolism during normal brain aging and in the brains of AD patients that result in accumulation of long-chain ceramides and cholesterol. Membrane-associated oxidative stress occurs in association with the lipid alterations, and exposure of hippocampal neurons to A␤ induces membrane oxidative stress and the accumulation of ceramide species and cholesterol. Treatment of neurons with ␣-tocopherol or an inhibitor of sphingomyelin synthesis prevents accumulation of ceramides and cholesterol and protects them against death induced by A␤. Our findings suggest a sequence of events in the pathogenesis of AD in which A␤ induces membrane-associated oxidative stress, resulting in perturbed ceramide and cholesterol metabolism which, in turn, triggers a neurodegenerative cascade that leads to clinical disease.amyloid ͉ apoptosis ͉ hippocampus ͉ lipid peroxidation ͉ sphingomyelin C hanges that occur in the brain during aging increase the risk of Alzheimer's disease (AD), a disorder involving the progressive deposition of amyloid ␤-peptide (A␤) and associated degeneration of neurons in brain regions involved in learning and memory (1). Two factors that are believed to contribute to neuronal dysfunction and degeneration in AD are increased oxidative stress and increased production of neurotoxic forms of A␤ (2). Alterations in lipid metabolism may also play roles in AD because the risk of AD is affected by inheritance of different isoforms of apolipoprotein E (3), changes in cholesterol metabolism can affect A␤ production in cell culture and in vivo (4-6), and drugs that lower cholesterol levels may reduce the risk of AD (7,8). However, a direct link between alterations in the metabolism of cholesterol and other membrane lipids in AD has not been established, and it is not known whether and how such lipid alterations might lead to neuronal dysfunction and death.Membrane microdomains that are rich in cholesterol and sphingolipids play important roles in various cellular signaling pathways (9, 10). Sphingomyelin is a major source of ceramides, lipid mediators that are generated when sphingomyelin is cleaved by sphingomyelinases, enzymes activated by inflammatory cytokines (11) and oxidative stress (12). Ceramides play important roles in regulating an array of physiological processes, including cell proliferation and differentiation, and a form of programmed cell death called apoptosis (13). Ceramides have been implicated in the pathological death of neurons that occurs in ischemic stroke (14) and Parkinson's disease (15). In the present study, we document significant increases in levels of m...