A functional polymorphism in the upstream regulatory region of the serotonin transporter gene (5-HTTLPR) has been recently reported to be associated with both unipolar and bipolar disorder.
A total of sixty-three genetic variants were selected on the basis of previous GWASs of MDD, SCZ, and BD as well as candidate-gene (SLC6A4, BDNF, DBH, and FKBP5) studies.
Age at onset (AAO) of bipolar disorders (BD) could be influenced both by a repeat length polymorphism (5HTTLPR) in the promoter region of the serotonin transporter gene (SLC6A4) and exposure to childhood trauma.
Allelic association case-control analysis of a deletion/insertion polymorphism in the serotonin transporter-linked polymorphic region (5-HTTLPR) has suggested associations with unipolar disorder, bipolar disorder, depression, and Alzheimer's disease.
Although it will be important to extend the present study in a larger sample, our initial results do not suggest any large association with alleles of the VNTR in the SERT gene and bipolar disorder in Indian patients.Am.J. Med.Genet.(Neuropsychiatr.Genet.)96:170-172, 2000.
An association study of bipolar mood disorder (type I) with the 5-HTTLPR serotonin transporter polymorphism in a human population isolate from Colombia.
Antidepressant-induced mania (AIM) has been described in bipolar disorder (BD) and has been associated with the short-allele of the serotonin transporter gene (5-HTT).
Associations of the serotonin transporter promoter polymorphism (5-HTTLPR) with bipolar disorder and treatment response: A systematic review and meta-analysis.
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.
Differential sampling procedures may influence the proportion of AAO subgroups in a given association study, and therefore these results may explain the conflicting results obtained in studies of the association between the SLC6A4 gene polymorphism and bipolar affective disorder (BPAD).
However, we found that CpG sites of SLC6A4, which were hypermethylated in patients with bipolar disorder, were hypomethylated in the neuroblastoma cells treated with mood stabilizers.
In this study, the 5-HTTLPR was estimated in 67 patients with bipolar mood disorder, receiving lithium carbonate for prophylactic purposes for the period of more than 5 years (mean 15 years).
Meta-analyses suggest small positive associations between the polymorphism in the serotonin transporter promoter region (5-HTTLPR) and bipolar disorder, suicidal behavior, and depression-related personality traits but not yet to MDD itself.
Nevertheless, the findings might suggest that alterations in the structure of 5-HTT are involved in the pathogenesis of bipolar disorder, which could have major implications in treatment.
Our study suggests that the markers examined thus far in COMT and SLC6A4 are not associated with pediatric bipolar disorder and that if the val66met marker in BDNF is associated with pediatric bipolar disorder the magnitude of the association is much smaller than first reported.