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Rate of familial amyotrophic lateral sclerosis: a systematic review and meta-analysis
  1. Susan Byrne1,3,
  2. Cathal Walsh2,
  3. Catherine Lynch1,
  4. Peter Bede1,3,
  5. Marwa Elamin1,3,
  6. Kevin Kenna3,
  7. Russell McLaughlin3,
  8. Orla Hardiman1,3
  1. 1Deparment of Neurology, Beaumont Hospital, Dublin, Ireland
  2. 2Department of Statistics, Trinity College, Dublin, Ireland
  3. 3Trinity College, Dublin, Ireland
  1. Correspondence to Dr S Byrne, Beaumont Hospital, Beaumont Rd, Dublin 9, Ireland; suabyrne{at}


Background The population rate of familial amyotrophic lateral sclerosis (FALS) is frequently reported as 10%. However, a systematic review and meta-analysis of the true population based frequency of FALS has never been performed.

Method A Medline literature review identified all original articles reporting a rate of FALS. Studies were grouped according to the type of data presented and examined for sources of case ascertainment. A systematic review and meta-analysis of reported rates of FALS was then conducted to facilitate comparison between studies and calculate a pooled rate of FALS.

Results 38 papers reported a rate of FALS. Thirty-three papers were included in analysis and the rate of FALS for all studies was 4.6% (95% CI 3.9% to 5.5%). Restricting the analysis to prospective population based registry data revealed a rate of 5.1% (95% CI 4.1% to 6.1%). The incidence of FALS was lower in southern Europe. There was no correlation between rate of FALS and reported SOD1 mutation rates.

Conclusion The rate of FALS among prospective population based registries is 5.1% (CI 4.1 to 6.1%), and not 10% as is often stated. Further detailed prospective population based studies of familial ALS are required to confirm this rate.

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  • Funding This work was supported by the IMNDA, IMNDRF and HRB funding.

  • Competing interests OH is a HRB Clinician Scientist. Her group has received unrestricted research grants from Merck Serono, Biogen Idec and Bayer Schering. She has received honoraria for providing expert advice to Merck Serono, Biogen Idec, Janssen Cilag, Allergan, Ono Pharmaceuticals and CytRx.

  • Provenance and peer review Not commissioned; externally peer reviewed.