C59 DIVERSE ETIOLOGIES AND CONVERGENCE OF PATHOLOGY IN ALS
SIDDIQUE T
NorthWestern University, Chicago, IL, USA
Email address for correspondence: [email protected]
Abstract not available.
C60 SIGMA RECEPTOR 1 MUTATIONS CAUSE FRONTOTEMPORAL LOBAR DEGENERATION–MOTOR NEURON DISEASE
SCHOFIELD PR1,2, LUTY AA1,2, KWOK JBJ1,2, DOBSON-STONE C1,2, LOY CT1,2, COUPLAND KG1,2, KARLSTROM H3, HUANG Y1,2, HALLUPP M1,2, McCANN H1,2, SOBOW T4, TCHORZEWSKA J4, MARUSZAK A5, BARCIKOWSKA M5, PANEGYRES PK6, ZEKANOWSKI C5, BROOKS WS1,2, WILLIAMS KL7,8, BLAIR IP7,8, MATHER KA2, SACHDEV PS2,9, HALLIDAY GM1,2
1Neuroscience Research Australia, Sydney, Australia, 2University of New South Wales, Sydney, Australia, 3Karolinska Institute, Stockholm, Sweden, 4University of Lodz, Lodz, Poland, 5Polish Academy of Sciences, Warsaw, Poland, 6Department of Health, Perth, Australia, 7Anzac Research Institute, Concord, Australia, 8University of Sydney, Sydney, Australia, 9Prince of Wales Hospital, Sydney, Australia
Email address for correspondence: [email protected]
Keywords: genetics, FTLD, neuropathology
Pathological ubiquitinated inclusion bodies observed in frontotemporal lobar degeneration (FTLD), the most common cause of early-onset dementia, and motor neuron disease (MND) contain TDP-43 and/or FUS proteins, suggesting that there may be a shared etiology between these disorders. Using a large FTLD-MND pedigree that showed significant linkage to chromosome 9p, our objective was to identify the causative gene using positional cloning. We identified a mutation (c.672*51G > T) in the 3′-untranslated region (3′-UTR) of the sigma nonopioid intracellular receptor 1 (SIGMAR1) gene in affected individuals from the FTLD-MND pedigree. This mutation was not found in over 2,500 neurologically normal chromosomes (1). Mutation screening of 26 FTLD probands, negative for MAPT and GRN mutations, and 158 unrelated cases of familial presenile dementia, negative for known dementia mutations, identified two additional 3′-UTR mutations, c.672*26C > T and c.672*47G > A. Screening a further 119 neuropathologically diagnosed neurodegeneration cases for mutations in SIGMAR1 identified one patient with the corticobasal degeneration form of FTLD-tau, with both tau and TDP-43 immunoreactive pathology, who had a 21 bp deletion in the 3′UTR (c.672*800_*820del). The c.672*51G > T mutation significantly increased gene expression in a luciferase reporter assay by 1.4-fold, corresponding with a significant 1.5- to 2-fold change in the SIGMAR1 transcript or Sigma-1 protein in lymphocyte or brain tissue. The c.672*800_*820del deletion mutation also resulted in a 1.5-fold increase in gene expression. However, the c.672*26C > T and c.672*47G > A mutations decreased luciferase activity by 0.8-fold. Neuropathological characterization of the brains of affected individuals showed that SIGMAR1 mutation carriers displayed a unique pathology with cytoplasmic inclusions, immunopositive for either TDP-43 or FUS, but not Sigma-1. Overexpression of SIGMAR1 in cell lines and Western blot studies were performed to identify the pathological mechanism of the mutation. Overexpression of SIGMAR1 shunted TDP-43 and FUS from the nucleus to the cytoplasm by 2.3-fold and 5.2-fold, respectively. Treatment of cells with Sigma-1 ligands significantly altered translocation of TDP-43 with the agonist opipramol causing 1.5-fold increased levels, and the antagonists AC915 and haloperidol causing up to 2-fold decreased levels of cytoplasmic TDP-43. Mutations in the SIGMAR1 gene have been shown to be a cause of a neuropathologically unique form of FTLD-MND, as well as in other degenerative conditions such as the corticobasal degeneration form of FTLD-tau. However, mutations in the SIGMAR1 gene do not appear to explain all cases of chromosome 9p-linked FTLD or MND, suggesting that there are additional causal genes to be discovered. Our findings also suggest that Sigma-1 drugs have potential for the treatment of the TDP-43/FUS proteinopathies.
Reference
- Luty AA, Kwok JBJ, Dobson-Stone C, et al. Annals of Neurology 2010;68:639–49.
C61 COMBINED GENOME-WIDE ANALYSIS IDENTIFIES UNC13A AND CHROMOSOME 9P21.1 AS SHARED LOCI FOR SUSCEPTIBILITY TO AMYOTROPHIC LATERAL SCLEROSIS AND FRONTOTEMPORAL LOBAR DEGENERATION
DIEKSTRA F1, VAN ES M1, ESTRADA K2, RIVADENEIRA F2, HOFMAN A2, UITTERLINDEN A2, ROBBERECHT W3,4, ANDERSEN P5, MELKI J6, MEININGER V7, HARDIMAN O8,9, LANDERS J10,11, BROWN JR. R10,11, SHATUNOV A12, AL-CHALABI A12, CHIÒ A13, THE INTERNATIONAL COLLABORATION FOR FRONTOTEMPORAL LOBAR DEGENERATION16, VAN SWIETEN J15, VAN DEN BERG L1, VELDINK J1
1Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands, 2Department of Epidemiology and Biostatistics, Erasmus University Medical Center Rotterdam, Rotterdam, The Netherlands, 3Department of Neurology, University Hospital Leuven, University of Leuven, Leuven, Belgium, 4Laboratory for Neurobiology, Vesalius Research Centre, Flanders Institute for Biotechnology (VIB), Leuven, Belgium, 5Department of Clinical Neuroscience, Umeå University, Umeå, Sweden, 6Department of Neuropediatrics, University of Paris, Bicetre Hospital, Paris, France, 7Department of Neurology, Université Pierre et Marie Curie, Hôpital de la Salpétrière, Paris, France, 8Department of Neurology, Beaumont Hospital, Dublin, Ireland, 9Department of Neurology, Trinity College, Dublin, Ireland, 10Department of Neurology, University of Massachusetts School of Medicine, Worcester, USA, 11Department of Neurology, Massachusetts General Hospital, Charlestown, USA, 12Medical Research Council Centre for Neurodegeneration Research, King's College London, Department of Clinical Neuroscience, Institute of Psychiatry, London, UK, 13Department of Neuroscience, University of Turin, and Azienda Ospedaliera Universitaria San Giovanni Batista, Turin, Italy, 14Department of Clinical Genetics, Section of Medical Genomics, VU University Medical Center, Amsterdam, The Netherlands, 15Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands, 16Multiple Institutions, Multiple, USA
Email address for correspondence: [email protected]
Keywords: frontotemporal lobar degeneration, meta-analysis, UNC13A
Background: Overlap exists for patients with Amyotrophic Lateral Sclerosis (ALS) and patients with frontotemporal lobar degeneration (FTLD), both clinically and pathologically as well as genetically. About 5-10% of ALS patients are diagnosed with FTLD, while FTLD patients can develop motor neuron symptoms. Furthermore, TDP-43 inclusions have been found in the majority of ALS patients and in cases of FTLD (FTLD-TDP). Previously, linkage studies in families with both ALS and FTLD have identified a locus on chromosome 9p13-21.
Objectives: We hypothesized that ALS and FTLD may be part of a spectrum of neurodegenerative disease and we sought to identify a common genetic basis for this neurodegenerative disease.
Methods: We obtained genome-wide single nucleotide polymorphism (SNP) genotype data from previously published studies on ALS and FTLD-TDP and performed genome-wide imputation based on the HapMap3r2 reference. After quality control, genome-wide data for ∼1.2M SNPs were available for nearly 4,400 ALS patients and over 13,000 controls and for 435 (pathology-proven) FTLD-TDP cases and 1,400 independent unaffected controls. Data were analyzed in a joint meta-analysis of both diseases and by using a conservative rank-products analysis, weighing ALS and FTLD sample sizes equally. Additionally, a subset of FTLD patients without motor neuron disease symptoms was analyzed.
Results: Joint analysis of ALS and FTLD identified SNPs in locus chromosome 9p21.1 (lowest p = 2.6 × 10−12) and SNP rs12608932 in gene UNC13A (p = 1.0 × 10−11) as shared genetic variants contributing to susceptibility to both neurodegenerative disorders. From the rank-products analysis we found the associations to be consistent. By analyzing a subset of FTLD patients without motor neuron disease signs, we found that individuals with ALS symptoms did not solely drive the signal for both loci.
Discussion and conclusions: Our study narrows the previously identified shared genetic locus on chromosome 9 and, additionally, implicates UNC13A as a shared risk locus further corroborating the role of UNC13A in neurodegeneration.
C62 POLYALANINE REPEAT EXPANSIONS IN NIPA1 ARE ASSOCIATED WITH ALS
VAN RHEENEN W1, BLAUW H1, VAN VUGHT P1, KOPPERS M1, DIEKSTRA F1, GROEN E1, VAN ES M1, WILLEMSE E1, STRENGMAN E2, LUDOLPH Ac3, WAIBEL S3, SCHULTE C4,5, ROBBERECHT W6,7, VAN DAMME P6,7, VELDINK J1, VAN DEN BERG LH1
1Department of Neurology, Rudolph Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands, 2Complex Genetics Section, Division of Biomedical Genetics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands, 3Department of Neurology, University of Ulm, Ulm, Germany, 4Department of Neurodegenerative Diseases, Hertie Institute of Clinical Brain Research, University of Tübingen, Tübingen, Germany, 5German Center for Neurodegenerative Diseases, Tübingen, Germany, 6Department of Neurology, University Hospital Leuven, Leuven, Belgium, 7Vesalius Research Center, Flanders Institute for Biotechnology, Leuven, Belgium
Email address for correspondence: [email protected]
Keywords: NIPA1, polyalanine, repeat expansion
Introduction: Genetic risk factors are thought to play a major role in the pathogenesis of ALS. Recent research has described deletions in NIPA1 increasing susceptibility for this disease. Mutations in this gene are known to cause hereditary spastic paraparesis type 6. In this study we investigate whether missense mutations in NIPA1 and expansions in its polyalanine repeat might play a role in ALS as well.
Methods: DNA samples were collected from 2293 ALS patients and 2777 healthy controls, of three different populations (Dutch, Belgian, German). All exons of NIPA1 were sequenced and fragment analysis was performed to determine the polyalanine repeat length. Alleles were grouped according to their length, with short alleles consisting of < 12, intermediate and long alleles of 12-13 and > 13 alanines respectively.
Results: Sequencing revealed 7 missense mutations in patients and 6 in controls (p = 0.59). In all populations the long repeat occurred more frequently in patients, 2.82% compared to 1.80% in controls (OR = 1.63, p = 0.0007). Patients with these long alleles showed worse median survival (HR 1.58, p = 0.0001) and had an earlier disease onset (HR 1.39, p = 0.005).
Conclusion: We found that missense mutations in NIPA1 do not play a major role in ALS. Instead, we found that short polyalanine expansions in NIPA1 are associated with ALS. In addition, these expansions are associated with an earlier disease onset and worse prognosis. These results further underscore the role of NIPA1 in ALS pathogenesis.