The Relationship Between Tryptophan Hydroxylase-2 Gene with Primary Insomnia and Depressive Symptoms in the Han Chinese Population

Abstract

TPHBackground:Insomnia often coexists with depression, and there iscompelling evidence for a genetic component in the etiologies of bothdisorders.Aims: To investigate the relationship between exonic variant(rs4290270) in the tryptophan hydroxylase-2 gene and primaryinsomnia and symptoms of depression in Han Chinese.Study Design: Case-control study.Methods: This study included 152 patients with primary insomniaand 164 age- and gender-matched normal controls. All patientswere investigated by polysomnography for 2 consecutive nights.The depressive symptoms were measured by using a 20-item ZungSelf-rating Depression Scale. Sleep quality was assessed with thePittsburgh Sleep Quality index. The genotypes of the TPH-2 genepolymorphism rs4290270 were determined by the polymerase chainreaction-restriction fragment length polymorphism method.Results: The genotype distributions of the tryptophan hydroxylase-2gene polymorphism rs4290270 were in Hardy-Weinberg equilibriumin both patients and controls (p>0.05). The allele and genotypedistributions of this variant were comparable between patients andcontrols in all subjects and between genders (all p>0.05). The impactof rs4290270 on self-rating depression scale score changes wasstatistically significant (p=0.002), with carriers of the A/A genotypehaving the highest self-rating depression scale score (mean ± standarddeviation: 52.73±12.88), followed by the A/T genotype (50.94±11.29,p=0.35) and the T/T genotype (43.48±7.78, p