Uher and McGuffin, 2008; Munafo et al., 2008]. Munafo et al. [2008] conducted a meta-analysis of published results, but only five studies reported data in a format that allowed inclusion: they conclude “some claims of replication seem not to be justified” with the interactions observed compatible with chance findings. More convincingly, a meta-analysis of 14 studies to March 2009 using the primary data, where available, found no evidence of an interaction [Risch et al., 2009]. Of all the studies to date, only one [Tsai et al., 2003] has considered the a/g single-nucleotide polymorphism (SNP) rs25531 in G × E studies of 5HTTLPR. The SNP lies within the L allele of 5HTTLPR, and L alleles with the rarer “g” allele at rs25531 are functionally equivalent to the S allele because of changes to the transcription factor-binding site altered by this SNP [Hu et al., 2006; Wendland et al., 2006].
