title: Aggregation of neurologic and neuropsychiatric disease in amyotrophic lateral sclerosis kindreds: a population-based case-control cohort study of familial and sporadic amyotrophic lateral sclerosis.
abstract: OBJECTIVE
  Amyotrophic lateral sclerosis (ALS) is associated with frontotemporal dementia (FTD) in 14% of cases. Five percent report a family history of ALS, and other ALS patients report a family history of other neurodegenerative diseases. The objective of this study was to conduct a family aggregation study of ALS, and neurodegenerative and neuropsychiatric conditions in ALS kindreds and matched healthy controls. The aim was to determine the true rate of familial ALS and the recurrence risk of ALS in family members, and to identify kindreds with increased aggregation of neurodegenerative and neuropsychiatric disease in the context of the recently described expanded hexanucleotide repeat in C9orf72.
  
  
  METHODS
  A prospective, population-based, case-control family aggregation study was conducted. Family history information was collected through questionnaires and interviews from ALS patients and matched controls. Cause of death was verified with death certification. The recurrence rate of ALS and the risk in family members of other neurodegenerative and neuropsychiatric disease was calculated using the relative risk (lambda) and cumulative risk using Kaplan-Meier analysis.
  
  
  RESULTS
  Medical histories from 9,684 first- and second-degree relatives of 172 ALS probands and 192 controls were obtained. Cause of death was verified in 2,494 cases. Sixteen percent (n=27) of ALS patients had a family history of ALS. The lifetime hazard ratio (HR) of developing ALS among first- and second-degree relatives was 34.3 (p<0.0001) in relatives of ALS patients with the C9orf72 repeat expansion, and 2.3 (p=0.019) in relatives of ALS patients without the expansion. The relatives of ALS patients also had an increased HR of developing a psychotic illness (HR=4.7, p=0.004, 95% confidence interval [CI]=1.6-12.3) and of suicide (HR=5.6, p<0.0001, 95% CI=2.4-12.9) INTERPRETATION: The true rate of familial ALS in Ireland is 16%. There is an overlap between ALS, FTD, and neuropsychiatric disease that is pronounced in kindreds with the C9orf72 repeat expansion, but is also present in kindreds of those without the C9orf72 expanded repeat.
authors.affiliation: Department of Neurology, Beaumont Hospital, Dublin, Ireland; Trinity Biomedical Sciences Institute, School of Medicine, Dublin, Ireland.
authors.forename: Susan
authors.initials: S
authors.lastname: Byrne
authors.forename: Mark
authors.initials: M
authors.lastname: Heverin
authors.forename: Marwa
authors.initials: M
authors.lastname: Elamin
authors.forename: Peter
authors.initials: P
authors.lastname: Bede
authors.forename: Catherine
authors.initials: C
authors.lastname: Lynch
authors.forename: Kevin
authors.initials: K
authors.lastname: Kenna
authors.forename: Russell
authors.initials: R
authors.lastname: MacLaughlin
authors.forename: Cathal
authors.initials: C
authors.lastname: Walsh
authors.forename: Ammar
authors.initials: A
authors.lastname: Al Chalabi
authors.forename: Orla
authors.initials: O
authors.lastname: Hardiman
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology* / Q000235:genetics; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D007494:Ireland / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000453:epidemiology* / Q000235:genetics; D011446:Prospective Studies; D012042:Registries; D012306:Risk; D011795:Surveys and Questionnaires