The serotonin transporter gene (SLC6A4) encodes a trans-membrane protein (5-HTT) that plays an important role in regulating serotonergic neurotransmission, which is known to be involved in many psychiatric disorders. A polymorphism in the transcriptional control region containing long (L) and short (S) variants (5-HTTLPR) as well as alleles of the variable number tandem repeats (VNTR) region were demonstrated. Higher serotonin levels among carriers of the S allele might exhibit increased liability of serotonin-mediated, psychopathology-like anxiety and depression and may impair social skills reflected by harm avoidance.
To analyze the data of alcohol-dependent, unrelated German individuals for a significant association between serotonin transporter gene and history of depression as well as TCI scales.
We characterized 368 alcohol-dependent participants by TCI and SSAGA/history of depression. HHT and VNTR genes were amplified by polymerase chain reaction.
No significant association was found between history of depression and 5-HTTLPR (F=0.42, P=0.65, d.f.=2) as well as between history of depression and VNTR (F=0.24, P=0.91, d.f.=2). As harm avoidance is often associated with history of depression, the TCI was used. Regarding the TCI temperament and character scale scores, no significant association was found between harm avoidance and this genetic variant 5-HTTLPR (F=0.55, P=0.57, d.f.=2), and between harm avoidance and VNTR (F=0.39, P=0.81, d.f.=2). Haplotype analysis showed significant relationship between low level of harm avoidance and haplotype S/12 (χ2=7.01, P=0.00). Haplotype analysis of history of depression (χ2=2.04, P=0.742) showed no significant result.
Our results indicate an association between S/12 haplotype of SLC6A4 and low level of harm avoidance.