Rate of familial amyotrophic lateral sclerosis: a systematic review and meta-analysis.
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.


METHODS
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.


CONCLUSIONS
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.
Deparment of Neurology, Beaumont Hospital, Beaumont Rd, Dublin 9, Ireland. suabyrne@gmail.com
Susan
S
Byrne
Cathal
C
Walsh
Catherine
C
Lynch
Peter
P
Bede
Marwa
M
Elamin
Kevin
K
Kenna
Russell
R
McLaughlin
Orla
O
Hardiman
D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology* / Q000235:genetics; D006801:Humans; D009154:Mutation; D013482:Superoxide Dismutase / Q000235:genetics
D013482:Superoxide Dismutase