Association study between plasma level of brain-derived neurotrophic factor and C270T polymorphism in schizophrenia patients with the symptoms of hallucination and delusion

Objective To study the relationship between C270T polymorphism of the brain-derived neurotrophic factor (BDNF) gene and the plasma BDNF level in the schizophrenia patients,and to clarify the association of BDNF and its gene with schizophrenia. Methods Total 104 schizophrenia patients with the symptoms of hallucination and delusion and 100 healthy normal subjects were recruited.Their blood samples were collected for plasma BDNF levels by ELISA and C270T polymorphism determination by PCR-RFLP.The differences of C270T genotype frequency,T allele frequency and plasma BDNF levels between the two groups were compared via χ² or t test. Results The case group had obviously higher C/T genotype frequency(34.6％) as compared with the control group(17.0％),P=0.013.The frequency of T allele in schizophrenia patients(20.2％) was significantly higher than healthy controls(10.5％),P=0.007.Plasma BDNF of C/T and T/T genotype in both groups[(0.85±0.13) ng/ml,(0.99±0.17)ng/ml] was significantly lower than that in C/C genotype[(1.21±0.28) ng/ml,(1.38±0.24) ng/ml),P＜0.001].In the same genotype,plasma BDNF of patients was obviously lower than that of healthy controls[C/C genotype:(1.21±0.28) ng/ml vs.(1.38±0.24) ng/ml,P＜0.001;C/T and T/T genotype:(0.85±0.13) ng/ml vs.(0.99±0.17) ng/ml,P＝0.005]. Conclusion T allele in the C270T site of BDNF gene may be associated with the susceptibility to schizophrenia via the reduction of BDNF expression.