Association between serotonin transporter gene polymorphism and chronic fatigue syndrome

Abstract Interaction between the hypothalamo–pituitary–adrenal axis and the serotonergic system is thought to be disrupted in chronic fatigue syndrome (CFS) patients. We examined a serotonin transporter (5-HTT) gene promoter polymorphism, which affects the transcriptional efficiency of 5-HTT , in 78 CFS patients using PCR amplification of the blood genomic DNA. A significant increase of longer (L and XL) alleic variants was found in the CFS patients compared to the controls both by the genotype-wise and the allele-wise analyses (both p χ 2 test and Fisher’s exact test). Attenuated concentration of extracellular serotonin due to longer variants may cause higher susceptibility to CFS.