Norepinephrine transporter gene polymorphism is not associated with susceptibility to major depression

The monoamine neurotransmitters serotonin, norepinephrine and dopamine have been implicated in the pathogenesis of depression, schizophrenia and mood disorders. The mechanism of action of certain antidepressant drugs, particularly the tricyclics and the newly available norepinephrine and serotonin reuptake inhibitors (NSRIs) drugs, venlafaxine and nefazodone, suggest that the norepinephrine transporter, which is a target for these antidepressant drugs, and its malfunction may be involved in major depression. In this association study, we tested the hypothesis that variants of the human norepinephrine transporter (NET) gene confer susceptibility to major depression. One hundred and five patients with major depression and 74 unrelated matched controls were analyzed for a silent 1287G/A polymorphism (NET-8) in exon 9 of the NET gene. No significant differences in genotype or allele frequencies were found between controls and patients, nor between subgroups of depressed patients classified by suicidal ideation. In addition, 60 controls and 60 patients were genotyped for a missense substitution Thr99Ile in exon 2 of the NET gene (NET-1), but only one control was heterozygous for this variant. These results suggest that the NET gene is unlikely to be involved in the susceptibility to major depression.