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Absence of consensus in diagnostic criteria for familial neurodegenerative diseases
  1. Susan Byrne1,2,
  2. Marwa Elamin1,2,
  3. Peter Bede1,2,
  4. Orla Hardiman1,2
  1. 1Trinity College Institute of Neurosciences, Beaumont Hospital, Trinity College, Dublin, Ireland
  2. 2Department of Neurology, Beaumont Hospital, Dublin 9
  1. Correspondence to Dr Susan Byrne, Beaumont Hospital, Dublin 9, Trinity College, Dublin 2, Ireland; suabyrne{at}


Background A small proportion of cases seen in neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS), Parkinson's disease and Alzheimer disease are familial. These familial cases are usually clinically indistinguishable from sporadic cases. Identifying familial cases is important both in terms of clinical guidance for family members and for gene discovery.

Method Surveys assessing the definition of familial amyotrophic lateral sclerosis (FALS) were completed by clinicians with an interest in ALS.

Results 95 surveys were completed by respondents from 15 countries. A third of total respondents stated that they thought that neurologists were using the same definition for FALS (33.3%, 30). No consensus was achieved among clinicians when provided with five different definitions for FALS. However, the preferred definition was ‘a patient with ALS with either a first or second degree relative also with ALS’ (37.8%, 31).

Conclusion There is no consensus on a standard definition for FALS among clinicians. It is likely that similar inconsistencies apply to other conditions, such as Parkinson's disease and Alzheimer disease, in which both familial and sporadic diseases occur. Inconsistent classification could hinder gene discovery.

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  • Statistical analysis was completed by Susan Byrne using SPSS V.16.0.

  • Funding This work was funded by the Health Research Board, Ireland. Prof Hardiman is an 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.

  • Competing interests None.

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

  • Data sharing statement Statistical and data tables are available from the corresponding author (suabyrne{at}