We analyzed 62 genotyped variants within the selected genes (BDNF, NTRK2, SLC6A4, TPH2, P2RX7, DAOA, COMT, DISC1, and MAOA) against the presence of mood disorder, and in post-hoc analyses, specifically against bipolar disorder or major depressive disorder.
To evaluate the controversial, putative associations between the three common polymorphisms [promoter variable number tandem repeat (uVNTR), T941G, (CA) repeat] of monoamine oxidase A (MAOA) and mood disorders (major depressive or bipolar disorders, BPD) by systematically meta-analyzing published case-control association studies.
To evaluate the controversial, putative associations between the three common polymorphisms [promoter variable number tandem repeat (uVNTR), T941G, (CA) repeat] of monoamine oxidase A (MAOA) and mood disorders (major depressive or bipolar disorders, BPD) by systematically meta-analyzing published case-control association studies.
Furthermore, we performed a particular gene-gene interaction for the X-linked serotonergic genes (HTR2C and MAOA), and found no association among this intergenic haplotype combination and suicidal behaviour in bipolar disorder.
In order to test this hypothesis, we genotyped the 941T > G and the promoter VNTR polymorphisms in the MAOA gene and the Val 108/158 Met COMT polymorphism in 305 families with at least one member having bipolar disorder (BD).
Regarding MAOA, three meta-analyses with partially overlapping samples supported a modest effect of this gene in bipolar disorder in female Caucasians.
Our results suggest that MAOA gene variation may modulate the expression of some clinical aspects of severe mood disorders, especially in females, and support the existence of a genetic and aetiologic heterogeneity underlying the diagnoses of bipolar disorder and major depression.
The associations with the MAOA and serotonin transporter loci are consistent with previous data suggesting associations with susceptibility to bipolar affective disorder.Am.J. Med.Genet.(Neuropsychiatr.Genet.)96:36-42, 2000
Given the link between abnormalities in serotonergic neurotransmission and bipolar disorder, a candidate gene association approach was applied to study the involvement of the monoamine oxidase A (MAOA) gene, which codes for a catabolic enzyme of serotonin, in the susceptibility to bipolar disorder.
This study examined whether this functional polymorphism of the MAOA gene is associated with the risk of developing mood disorders in a Japanese sample of 161 patients with bipolar disorder, 98 with unipolar depression, and 258 controls.
Associations of bipolar affective disorder in pooled male and female groups were found with the MAOA microsatellite in both the Caucasian (P < 0.02) and the Japanese (P < 0.02) meta-analyses.
These data do not support the association of MAO-A or B with bipolar affective disorder but do demonstrate that undetected population stratification can be an important source of bias in case-control studies.