TCF4 and schizophrenia: This points to the association between schizophrenia and TCF4 not being mediated by a relatively common non-synonymous variant, or by a variant that alters mRNA expression, as measured in adult human brain; however, it is still possible that the risk allele at this locus exerts effects on expression exclusively in a developmental context, in cell types or brain regions not adequately represented in Williams’ et al. analysis [286], or through post-transcriptional effects, for example, in the abundance of the protein or its sub-cellular distribution.