Identification of TNFA influencing MDD risk and clinical features in Han Chinese

Our recent genetic-neuroimaging study observed that the rs1799724 polymorphism within the TNFA gene encoding TNF-α selectively affects the anatomy of visual cortex in patients with MDD. In this study, we hypothesized that TNFA is risk factor to MDD, and TNFA rs1799724 polymorphism may be a susceptibility locus for this disorder and its clinical features.

We enrolled 807 MDD samples and 822 healthy volunteers in Eastern China. There were 104 drug-naïve first episode MDD patients recruited. The Hamilton Rating Scale for Depression -17 (HRSD-17) and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) were performed to evaluate the severity of depressive symptoms and cognitive function, respectively.

Patients with MDD have higher levels of TNFA than healthy controls (F = 20.78, P < 0.01). There were no significant differences in genotype or allele distributions of the rs1799724 polymorphism between the MDD and control groups. MDD patients with T/T or T/C genotypes of rs1799724 polymorphism have higher somatic factor and total scores of HAMD than those with C/C genotype. The patients with T/T or T/C genotypes have significantly higher TNFA mRNA levels than those with C/C genotype (F = 4.91, P = 0.029).

Our findings supported that TNFA may have an important role in the pathophysiology of MDD. Although SNP rs1799724 is not an etiological factor for MDD in Han Chinese, this SNP may be associated with somatic symptom in patients with MDD.