Sequence variants and haplotype analysis of serotonin transporter gene and association with bipolar affective disorder in Taiwan.
OBJECTIVE
Serotonin transporter (SLC6A4) is responsible for serotonin re-uptake into presynaptic terminals, thus fine-tuning brain serotonergic neurotransmission. Current studies have found associations of SLC6A4 polymorphisms with several psychiatric traits including bipolar affective disorder (BPD) in various populations; however, studies with contradictory results were also reported. This study examined the role of SLC6A4 in etiology of BPD in a Taiwanese population.


METHODS
Ten markers including two variable number tandem repeat and eight single nucleotide polymorphisms (SNPs) on the SLC6A4 gene were used to study the genetic association with 90 unrelated BPD, type I patients and 103 controls.


RESULTS
Two SNPs were not informative in a Taiwanese population and the other eight polymorphic markers were analyzed by Fisher's exact test and haplotype analysis. No association was detected for any single SLC6A4 marker and BPD. Additional statistic analyses including other factors also showed lack of association between the SLC6A4 gene polymorphisms and BPD. Significant linkage disequilibrium was obtained among eight SLC6A4 markers and eight common haplotypes were constructed that can be found in 95% of the total subjects. The four commonest haplotypes in both patients and controls were identical. However, the fifth commonest haplotype differed in patients and controls and was significantly associated with a protection from BPD.


CONCLUSIONS
This study suggested that a particular SLC6A4 haplotype harboring functional sequence variant could play a significant role in BPD etiology in Taiwan. However, due to its modest sample size, the conclusion is not final and should be confirmed in the future studies.
Sun
H Sunny
HS
Institute of Molecular Medicine, National Cheng Kung University Medical College, Tainan, Taiwan. hssun@mail.ncku.edu.tw
Wang
Hui-Chung
HC
Lai
Te-Jen
TJ
Wang
Tso-Jen
TJ
Li
Chih-Ming
CM
D001714:Bipolar Disorder / Q000453:epidemiology / Q000209:etiology*; D002352:Carrier Proteins / Q000235:genetics*; D016022:Case-Control Studies; D005838:Genotype; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D018598:Minisatellite Repeats / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012701:Serotonin / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins; D013624:Taiwan / Q000453:epidemiology
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin