[12], [13] The magnitude and duration of 5-HT actions depend mostly on 5-HT transporter (SERT), which mediates the extracellular reuptake of 5-HT, thus ensuring its recycling and catabolic breakdown. [14], [15] Since abnormalities in 5-HT reuptake have the potential of altering the enteric serotonergic signalling, leading to motor, secretory and sensory gut dysfunctions, it has been suggested that genetic or epigenetic SERT variations might contribute to the pathogenesis or clinical presentation of IBS. [7], [16]. This evidence concerns the gene SLC6A4 and irritable bowel syndrome.