title: The influence of serotonin transporter polymorphisms on cortical activity: a resting EEG study.
abstract: BACKGROUND
  The serotonin transporter gene (5-HTT) is a key regulator of serotonergic neurotransmission and has been linked to various psychiatric disorders. Among the genetic variants, polymorphisms in the 5-HTT gene-linked polymorphic region (5-HTTLPR) and variable-number-of-tandem-repeat in the second intron (5-HTTVNTR) have functional consequences. However, their genetic impact on cortical oscillation remains unclear. This study examined the modulatory effects of 5-HTTLPR (L-allele carriers vs. non-carriers) and 5-HTTVNTR (10-repeat allele carriers vs. non-carriers) polymorphism on regional neural activity in a young female population.
  
  
  METHODS
  Blood samples and resting state eyes-closed electroencephalography (EEG) signals were collected from 195 healthy women and stratified into 2 sets of comparisons of 2 groups each: L-allele carriers (N=91) vs. non-carriers for 5-HTTLPR and 10-repeat allele carriers (N=25) vs. non-carriers for 5-HTTVNTR. The mean power of 18 electrodes across theta, alpha, beta, gamma, gamma1, and gamma2 frequencies was analyzed. Between-group statistics were performed by an independent t-test, and global trends of regional power were quantified by non-parametric analyses.
  
  
  RESULTS
  Among 5-HTTVNTR genotypes, 10-repeat allele carriers showed significantly low regional power at gamma frequencies across the brain. We noticed a consistent global trend that carriers with low transcription efficiency of 5-HTT possessed low regional powers, regardless of frequency bands. The non-parametric analyses confirmed this observation, with P values of 3.071×10-8 and 1.459×10-12 for 5-HTTLPR and 5-HTTVNTR, respectively.
  
  
  CONCLUSIONS
  Our analyses showed that genotypes with low 5-HTT activity are associated with less local neural synchronization during relaxation. The implication with respect to genetic vulnerability of 5-HTT across a broad range of psychiatric disorders is discussed. Given the low frequency of 10-repeat allele of 5-HTTVNTR in our research sample, the possibility of false positive findings should also be considered.
authors.affiliation: Department of Psychiatry, Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, Taoyuan County, Taiwan.
authors.forename: Tien-Wen
authors.initials: TW
authors.lastname: Lee
authors.forename: Younger W Y
authors.initials: YW
authors.lastname: Yu
authors.forename: Chen-Jee
authors.initials: CJ
authors.lastname: Hong
authors.forename: Shih-Jen
authors.initials: SJ
authors.lastname: Tsai
authors.forename: Hung-Chi
authors.initials: HC
authors.lastname: Wu
authors.forename: Tai-Jui
authors.initials: TJ
authors.lastname: Chen
mesh_terms: D000483:Alleles; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D005838:Genotype; D006801:Humans; D020641:Polymorphism, Single Nucleotide; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D055815:Young Adult
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins