Objective: To assess whether the promoter region of the serotonin transporter gene (5-HTTLPR) and G-protein β3-subunit (GNβ3 C825T) polymorphisms are associated with depressive disorder and explore the genetic mechanism concerning the pathogenesis of this disorder.
Methods: The genotypes were determined with polymerase chain reaction and allele-specific restriction enzyme analysis. Patients suffering from depression (n=184) and sex and age-matched controls (n=158) were compared in this study.
Results: The frequencies of 5-HTTLPR SS and GNβ3 825TT genotypes and 5-HTTLPR S and GNβ3 825T alleles in patients suffering from depression were significantly higher than those in the controls (P<0.01). Combined genotype analysis showed that individuals with both 5-HTTLPR S and GNβ3 825T alleles (odds ratio=3.25, P=0.002) had a risk of depressive disorder higher than those with 5-HTTLPR S (odds ratio=1.817, P=0.01) or GNβ3 825T alleles (odds ratio=2.214, P=0.001) alone.
Conclusions: These results indicated that the etiology of depressive disorder is associated with 5-HTTLPR and GNβ3 C825T polymorphisms. Our data also suggests that an interaction effect may exist between the 5-HTTLPR S allele and GNβ3 825T allele in increasing the risk of depressive disorder.