The serotonin transporter (5-HTTLPR) and brain-derived neurotrophic factor (BDNF) gene polymorphisms have been associated with risk for affective disorders and functional variability of the amygdala.
Such alterations suggest a broad role of the 5-HTT gene in brain function that may be associated with the genetic susceptibility for mood disorders such as depression.
A polymorphism in the 5'-flanking regulatory region of the 5-HTT gene that results in allelic variation of 5-HTT expression is associated with anxiety-related personality traits and may influence the risk of developing affective disorders.
The serotonin transporter (5-HTT) gene contains a variable number tandem repeat (VNTR) domain within intron 2 that is often associated with a number of neurological conditions, including affective disorders.
Given that the 5-HTTLPR polymorphism has been associated with mood disorders, it is plausible that the abnormal pattern of regional brain activity detected here, in children carrying the S allele, increases susceptibility to emotional dysregulation and depressive symptoms.
These results suggest that neuroticism mediates the association between 5HTT-LPR genotype and lifetime major depression, consistent with models of the aetiology of depression which suggest that anxiety-related personality traits represent a substantial risk factor for affective disorder.
This single nucleotide polymorphism in the 3' untranslated region of the hSERT gene should provide a useful genetic marker in the evaluation of hSERT as a candidate gene influencing susceptibility to mood disorders.
In this overview, currently known clinically relevant GR and MR polymorphisms are discussed in relation to mood disorders (both unipolar depression and bipolar disorder) and cognitive function.
Environmental vulnerability factors such as adverse childhood experiences in interaction with genetic risk variants, e.g., the serotonin transporter gene linked polymorphic region (5-HTTLPR), are assumed to play a role in the development of anxiety and affective disorders.
There is some evidence suggesting that a polymorphism of variable number of tandem repeats (VNTR) in the second intron of the serotonin transporter (5-HTT) gene and another variation which lies 1.2 kb upstream of the promoter of the gene (5-HTTLPR) are associated with affective disorders.
In particular, the presence of one or two copies of the short (s) allele of the 5-HTTLPR polymorphism has been associated with reduced serotonin transporter expression and function, and vulnerability to affective disorders.
Although the serotonin transporter length polymorphic region (5-HTTLPR) polymorphism is an extensively-investigated genetic marker of anxiety related personality traits (neuroticism and harm avoidance) and affective disorders, effect sizes in meta-analyses are small, if present at all, and all available primary studies to date lack mandatory statistical power.
Further, 2 genetic polymorphisms: the 5-HTTLPR and the brain-derived neurotrophic factor (BDNF) Val66Met polymorphisms were not directly associated with familial risk for affective disorder and did not predict illness onset.
A deletion polymorphism in the serotonin transporter-linked polymorphic region (5-HTTLPR) has been associated with vulnerability to affective disorders, yet the mechanism by which this gene confers vulnerability remains unclear.
Negative affect such as depression and anxiety has been reported to be associated with morbidity and mortality, and polymorphisms of the serotonin transporter (5HTT) gene may be associated with such affect disorders.
Analysis did not show any statistically significant differences in the mean levels of anxiety, and mood disorders in women in relation to genotypes of the 5-HTTLPR (SLC6A4) polymorphism and the 30-bp VNTR polymorphism in the MAO A promoter region.
A functional polymorphism within the serotonin transporter gene (5-HTTLPR) has been reported to modulate emotionality and risk for affective disorders.
The alleged association between the serotonin-transporter-linked polymorphic region (5-HTTLPR) and amygdala activation forms a cornerstone of the common view that carrying the short allele of this polymorphism is a potential risk factor for affective disorders.
an association was found between 5-HTTLPR polymorphism and scores on three MMPI scales: Psychopathic deviance, Paranoia and Schizophrenia in patients with affective disorders and S chizophrenia in normal subjects.