It would, therefore, appear that the mechanistic advantages of escitalopram over citalopram, in terms of increased potency (Hyttel et al., 1992) and its known effect on the SERT through an affinity-modulating allosteric site (Chen et al., 2005), translate into clinical benefits in patients with MDD, as demonstrated in the pooled analysis by Llorca et al. The gene discussed is SLC6A4; the disease is major depressive disorder.