The serotonin transporter (5HTT) is a key regulator of serotonergic neurotransmission, localized to 17p13 and consisting of 14 exons and a single promoter. The 5HTTLPR (5HTT linked polymorphic region) is a well-explored genetic marker contributing to childhood temperament. Variation in the promoter region of the gene results in two main variants, a short and a long allele; presence of the short allele results in lower serotonin transporter availability. The short variant has 12 copies, and the long variant 14 copies, of a 22-bp repeat element. The short allele appears to exert a similar effect on temperament for both males and females (Munafo, Clark, & Flint, 2004). In the current report, we focus on contrasts between individuals with at least one short allele and those with no short alleles.
