title: The Role of APOE in the Occurrence of Frontotemporal Dementia in Amyotrophic Lateral Sclerosis.
abstract: OBJECTIVE
  Amyotrophic lateral sclerosis (ALS) is a heterogeneous disease with a wide spectrum of involvement of cognitive functions. The mechanisms of this heterogeneity are still largely unknown, but genetic variants may account for this variability.
  
  
  OBJECTIVE
  To assess the influence of the apolipoprotein E (APOE) and C9ORF72 genotypes on cognitive impairment in a population-based series of Italian patients with ALS.
  
  
  METHODS
  All 504 patients with ALS living in Piemonte, Italy, diagnosed between January 1, 2009, and December 31, 2013, and identified through the Piemonte and Valle d'Aosta register for ALS, were eligible to participate in the study. Controls were 223 age- and sex-matched individuals identified through the patients' general practitioners. Data analysis was performed from June 1 to December 31, 2014.
  
  
  METHODS
  The presence of APOE and C9ORF72 genotypes was assessed. Patients were cognitively classified as having ALS with normal cognition, ALS with frontotemporal dementia (FTD), ALS with executive or nonexecutive impairment, and ALS with behavioral impairment.
  
  
  RESULTS
  Of the 504 patients with incident ALS, 357 (70.8%) were included in the study; 154 were women, 203 were men, they had a mean (SD) age at onset of 64.8 (10.2) years, and 37 of them carried a C9ORF72 repeat expansion. Cognitive testing revealed that 184 patients (51.5%) had ALS with normal cognition, 51 (14.3%) had ALS with FTD, 103 (28.9%) had ALS with executive or nonexecutive impairment, and 19 (5.3%) had ALS with behavioral impairment. Distribution of APOE haplotypes did not significantly differ between patients and controls or among patients with different levels of cognitive impairment. According to multivariate logistic regression, the presence of C9ORF72 repeat expansions was the strongest determinant of FTD (odds ratio, 13.08; 95% CI, 4.75-36.02; P < .001); however, the presence of an APOE ε2 allele significantly increased the risk of FTD (odds ratio, 2.61; 95% CI, 1.14-6.10; P = .03). Presence of an APOE ε4 allele was ineffectual.
  
  
  CONCLUSIONS
  C9ORF72 repeat expansions have a primary role in increasing the risk of cognitive impairment in patients with ALS; the APOE ε2 allele, to a lesser extent, also increases the risk of FTD. These study findings highlight the importance of considering the genetic background of patients with ALS when analyzing the putative effect of genetic modifiers.
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy2The Azienda Ospedaliero Universitaria Città della Salute e della Scienza di Torino, Torino, Italy3The Neuroscience Institute of Torino, Torino, Italy4The In.
authors.forename: Adriano
authors.initials: A
authors.lastname: Chiò
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Maura
authors.initials: M
authors.lastname: Brunetti
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Barberis
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Iazzolino
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Montuschi
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Ilardi
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Cammarosano
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Canosa
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Moglia
authors.affiliation: ALS Center, "Rita Levi Montalcini" Department of Neuroscience, University of Torino, Torino, Italy2The Azienda Ospedaliero Universitaria Città della Salute e della Scienza di Torino, Torino, Italy3The Neuroscience Institute of Torino, Torino, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Calvo
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D053329:Apolipoprotein E2 / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics; D000073885:C9orf72 Protein; D015331:Cohort Studies; D005260:Female; D057180:Frontotemporal Dementia / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D005819:Genetic Markers / Q000235:genetics*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011506:Proteins / Q000235:genetics
chemical_list: D053329:Apolipoprotein E2; D001057:Apolipoproteins E; D000073885:C9orf72 Protein; C568651:C9orf72 protein, human; D005819:Genetic Markers; D011506:Proteins