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Balkan Med J. 2018 Nov 15;35(6):412-416. doi: 10.4274/balkanmedj.2017.1406. Epub 2018 Jun 28.

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

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Department of Medical Psychology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
Department of Neurology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China



Insomnia often coexists with depression, and there is compelling evidence for a genetic component in the etiologies of both disorders.


To investigate the relationship between exonic variant (rs4290270) in the tryptophan hydroxylase-2 gene and primary insomnia and symptoms of depression in Han Chinese.

Study Design:

Case-control study.


This study included 152 patients with primary insomnia and 164 age- and gender-matched normal controls. All patients were investigated by polysomnography for 2 consecutive nights. The depressive symptoms were measured by using a 20-item Zung Self-rating Depression Scale. Sleep quality was assessed with the Pittsburgh Sleep Quality index. The genotypes of the TPH-2 gene polymorphism rs4290270 were determined by the polymerase chain reaction-restriction fragment length polymorphism method.


The genotype distributions of the tryptophan hydroxylase-2 gene polymorphism rs4290270 were in Hardy-Weinberg equilibrium in both patients and controls (p>0.05). The allele and genotype distributions of this variant were comparable between patients and controls in all subjects and between genders (all p>0.05). The impact of rs4290270 on self-rating depression scale score changes was statistically significant (p=0.002), with carriers of the A/A genotype having the highest self-rating depression scale score (mean ± standard deviation: 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<0.01), and this impact was more obvious in women (p<0.001).


The tryptophan hydroxylase-2 gene polymorphism rs4290270 may not be a susceptibility locus for primary insomnia in Han Chinese, but it may be a marker of depressive symptoms.


Primary insomnia; Depressive disorder; TPH2 protein

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