The role of genetic polymorphisms in response to intervention has been highlighted and explored in prior research (IJzendoorn, et al., 2012). One genetic polymorphism that has received attention is the “s” allele in the promoter region of the serotonin transporter gene (SLC6A4), also referred to as the 5-HTT-linked polymorphic region (i.e., the 5-HTTLPR), a key regulator of serotonergic neurotransmission. This polymorphism results in two common variants, a long (l) and a short (s) allele, as well as some less common variants (e.g., the very long (vl) allele), and some variations with less pronounced effects on gene expression (i.e., the A/G substitution, see Philibert et al. 2008). The “s” variant is associated with lower availability of 5-HTT and reduced efficiency of 5-HTT reuptake.
