title: Sequence variations in C9orf72 downstream of the hexanucleotide repeat region and its effect on repeat-primed PCR interpretation: a large multinational screening study.
abstract: A large GGGGCC-repeat expansion mutation (HREM) in C9orf72 is the most common known cause of ALS and FTD in European populations. Sequence variations immediately downstream of the HREM region have previously been observed and have been suggested to be one reason for difficulties in interpreting RP-PCR data. Our objective was to determine the properties of these sequence variations with regard to prevalence, the range of variation, and effect on disease prognosis. We screened a multi-national cohort (n = 6981) for the HREM and samples with deviant RP-PCR curves were identified. The deviant samples were subsequently sequenced to determine sequence alteration. Our results show that in the USA and European cohorts (n = 6508) 10.7% carried the HREM and 3% had a sequence variant, while no HREM or sequence variants were observed in the Japanese cohort (n = 473). Sequence variations were more common on HREM alleles; however, certain population specific variants were associated with a non-expanded allele.In conclusion, we identified 38 different sequence variants, most located within the first 50 bp downstream of the HREM region. Furthermore, the presence of an HREM was found to be coupled to a lower age of onset and a shorter disease survival, while sequence variation did not have any correlation with these parameters.
authors.affiliation: a Department of Pharmacology and Clinical Neuroscience , Umeå University , Umeå , Sweden.
authors.forename: Angelica
authors.initials: A
authors.lastname: Nordin
authors.affiliation: b Division of Neurology, Department of Internal Medicine , Jichi Medical University , Tochigi , Japan.
authors.forename: Chizuru
authors.initials: C
authors.lastname: Akimoto
authors.affiliation: c Department of Chemistry , Umeå University , Umeå , Sweden.|d Computational Life Science Cluster (CLIC) , Umeå University , Umeå , Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Wuolikainen
authors.affiliation: a Department of Pharmacology and Clinical Neuroscience , Umeå University , Umeå , Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Alstermark
authors.affiliation: e Department of Medical Biosciences , Umeå University , Umeå , Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Forsberg
authors.affiliation: f Department of Neurology , Central Hospital of Lapland , Rovaniemi , Finland.
authors.forename: Peter
authors.initials: P
authors.lastname: Baumann
authors.affiliation: g Institute of Physiology and Institute of Molecular Medicine , University of Lisbon , Lisbon , Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Pinto
authors.affiliation: g Institute of Physiology and Institute of Molecular Medicine , University of Lisbon , Lisbon , Portugal.|h Department of Neurosciences , Hospital de Santa Maria-CHLN , Lisbon , Portugal.
authors.forename: Mamede
authors.initials: M
authors.lastname: de Carvalho
authors.affiliation: i Department of Neurology , Ulm University , Ulm , Germany.
authors.forename: Annemarie
authors.initials: A
authors.lastname: Hübers
authors.affiliation: a Department of Pharmacology and Clinical Neuroscience , Umeå University , Umeå , Sweden.
authors.forename: Frida
authors.initials: F
authors.lastname: Nordin
authors.affiliation: i Department of Neurology , Ulm University , Ulm , Germany.
authors.forename: Albert C
authors.initials: AC
authors.lastname: Ludolph
authors.affiliation: i Department of Neurology , Ulm University , Ulm , Germany.
authors.forename: Jochen H
authors.initials: JH
authors.lastname: Weishaupt
authors.affiliation: j Outpatient Department for ALS and other Motor Neuron Diseases , Charité-Universitätsmedizin Berlin , Berlin , Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Meyer
authors.affiliation: k Universitätsklinik Bochum , Bochum , Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Grehl
authors.affiliation: l Department of Neurology , Neuromuscular Center, Basel University Hospital, University Basel , Basel , Switzerland.
authors.forename: Kathi
authors.initials: K
authors.lastname: Schweikert
authors.affiliation: m Kantonsspital St. Gallen , Neuromuscular Disease Centre/ALS Clinic , Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Weber
authors.affiliation: m Kantonsspital St. Gallen , Neuromuscular Disease Centre/ALS Clinic , Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Burkhardt
authors.affiliation: m Kantonsspital St. Gallen , Neuromuscular Disease Centre/ALS Clinic , Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Neuwirth
authors.affiliation: n Department of Neurology , Akershus University Hospital , Lørenskog , Norway.|o Institute of Clinical Medicine , University of Oslo , Norway.
authors.forename: Trygve
authors.initials: T
authors.lastname: Holmøy
authors.affiliation: b Division of Neurology, Department of Internal Medicine , Jichi Medical University , Tochigi , Japan.
authors.forename: Mitsuya
authors.initials: M
authors.lastname: Morita
authors.affiliation: p Department of Neurology , Haukeland University Hospital , Bergen , Norway.|q Department of Clinical Medicine , University of Bergen , Bergen , Norway.
authors.forename: Ole-Bjørn
authors.initials: OB
authors.lastname: Tysnes
authors.affiliation: r Department of Neurology , University of Miami , Miami , FL , USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Benatar
authors.affiliation: r Department of Neurology , University of Miami , Miami , FL , USA.
authors.forename: Joanne
authors.initials: J
authors.lastname: Wuu
authors.affiliation: s Department of Neurology , Hospital for Special Surgery , New York , USA.|t Department of Neurology , New York-Presbyterian Hospital, Weill-Cornell Medical Center , New York , USA.
authors.forename: Dale J
authors.initials: DJ
authors.lastname: Lange
authors.affiliation: u Department of Neurology , Lillebælt Hospital , Vejle , Denmark.
authors.forename: Carsten
authors.initials: C
authors.lastname: Bisgård
authors.affiliation: u Department of Neurology , Lillebælt Hospital , Vejle , Denmark.|v Department of Neurobiology , Institute of Molecular Medicine, University of Southern Denmark , Odense , Denmark , and.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Asgari
authors.affiliation: w Department of Neurology , Mikkeli Central Hospital , Finland.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Tarvainen
authors.affiliation: e Department of Medical Biosciences , Umeå University , Umeå , Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Brännström
authors.affiliation: a Department of Pharmacology and Clinical Neuroscience , Umeå University , Umeå , Sweden.|i Department of Neurology , Ulm University , Ulm , Germany.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Andersen
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology / Q000235:genetics*; D001483:Base Sequence; D000073885:C9orf72 Protein / Q000235:genetics*; D015331:Cohort Studies; D042622:DNA Repeat Expansion; D005260:Female; D057180:Frontotemporal Dementia / Q000235:genetics; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D000073885:C9orf72 Protein; C568651:C9orf72 protein, human
keywords: ALS; C9orf72; FTD; RP-PCR interpretation; variants