The present study is limited by the sample size of the clinical trial, which particularly affected some of the subgroups (Kranzler et al. 2011). Further, this report is based on a secondary analysis using data collected in a clinical trial in which age of onset was defined a priori using DSM-IV criteria for AD. Because the effects that we observed were limited to L′-allele homozygotes, additional pharmacogenetic studies are needed to validate these findings.
