title: Using meta-analysis to explain the diversity of results in genetic studies of late-onset Alzheimer's disease and to identify high-risk subgroups.
abstract: In late-onset Alzheimer's disease, there is a puzzling inconsistency between the findings of case-control studies of most proposed risk genes, except apolipoprotein E epsilon4. This inconsistency may stem from the failure to define the genetic and non-genetic interactions that affect the disease association of each particular susceptibility gene. Such interactions will limit the influence of the gene to a 'relevant subset' of vulnerable people. The relevant subsets for many risk genes will be narrow, compared to that of apolipoprotein E epsilon4. Studies may therefore miss the association or even suggest that a risk gene is protective. In these circumstances, the precise composition of a cohort is critical and defining the relevant subset is crucial. We illustrate how such definition may be achieved through meta-analysis. We take as an example the butyrylcholinesterase K variant, whose association with Alzheimer's disease may now be provisionally defined. This analysis leads to the identification of a potentially high-risk group: over 75 year old male carriers of both apolipoprotein E epsilon4 and butyrylcholinesterase K variant.
authors.affiliation: Oxford Project To Investigate Memory and Ageing (OPTIMA), Radcliffe Infirmary, Oxford, UK. donald.lehmann@pharm.ox.ac.uk
authors.forename: D J
authors.initials: DJ
authors.lastname: Lehmann
authors.forename: J
authors.initials: J
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: McBroom
authors.forename: A D
authors.initials: AD
authors.lastname: Smith
mesh_terms: D017668:Age of Onset; D000368:Aged; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000235:genetics*; D006801:Humans; D012307:Risk Factors