Lack of association between the norepinephrine transporter gene and major depression in a Han Chinese population

Objective Although the physiological mechanisms contributing to the development of major depression remain unclear, several lines of evidence suggest that the catecholaminergic system involving the norepinephrine transporter (NET) is implicated in the etiology of major depression. This study aims to determine whether major depression is associated with the NET gene in a Han Chinese population. Methods We analyzed the NET promoter T-182C polymorphism and another silent polymorphism G1287A in exon 9 of the NET gene with a polymerase chain reaction (PCR)-based method in 216 patients with major depression and 210 unrelated, age-and sex-matched healthy control subjects. We interviewed all subjects with the Chinese Version of the Modified Schedule of Affective Disorders and Schizophrenia-Lifetime; major depressive disorder was diagnosed according to DSM-IV criteria. In addition, to reduce the clinical heterogeneity, we performed a subtype analysis with clinically important variables, such as family history of major affective disorder and age at onset of major depression. Results No significant difference was observed between the patients and healthy control subjects in the genotype distributions and allele frequencies for the investigated NET polymorphisms. Similarly, no significant differences were found between more homogeneous subgroups of patients and normal control subjects. Conclusions This study suggests that the investigated polymorphisms in the NET gene are not major risk factors in increasing susceptibility to either major depression or its clinical subtypes in a Han Chinese population. However, larger replication studies with different ethnic samples are needed.