An Association Study Of BDNF Va166Met Polymorphism And Schizophrenia In A Chinese Han Population

ObjectiveAlthough several lines of evidences suggested that the BDNF Val66Met polymorphism may be involved in the pathophysiology of schizophrenia, this association remains controversial. Besides, previous studies focused on this polymorphism and clinical symptoms of schizophrenia were deficiency. We aimed to investigate the genetic association between the BDNF Val66Met polymorphism and schizophrenia and to explore whether this polymorphism could influence the severity of clinical symptoms in schizophrenia patients in a Han Chinese population.MethodsIn the present case-control study, a total of456schizophrenia patients and483normal controls were recruited. The demographic information of all the subjects was tested by a self-made general information questionnaire. The Positive and Negative Syndrome Scale (PANSS) was used to assess patients’psychotic symptoms.5ml of venous blood samples were collected into tubes containing EDTAK2at7am. Gently rock the tubes several times immediately after collection of blood for anti-coagulation. Centrifuge at3000×g for10minutes and collect the white blood cell which would be kept at-70℃. Genotyping of BDNF Val66Met polymorphism was carried out in samples by the fluorescence resonance energy transfer method (FRET). All statistical analyses were performed using SPSS16.0software. Two-sample/group t-test for independent samples, one-way ANOVA and Spearman rank correlation analysis were applied in this study. A multiple linear regressions were performed to analyze the contribution of different variables on the severity of symptoms of schizophrenia phenotype. Results1. There were significant differences in the genotype distribution and allelic frequencies of the BDNF Val66Met polymorphism between the schizophrenia group and normal control(P<0.01). The frequency of the BDNF Met/Met genotype is significant higher in schizophrenia patients (33.3%) compared with normal group (24.0%). The Met allele in schizophrenia group (56%) is much higher than the normal group (49%).2. No significant difference has been establishment between the BDNF Val66Met polymorphism and gender, age, education years, family history, age onset, course and numbers of hospitalization of schizophrenia patients(P>0.05).3. The anxiety/depression factor, negative symptoms factor and total score of PANSS in schizophrenia patients were significantly different among the three genetic groups and there were no difference in positive symptoms factor, excitement/hostile factor and cognitive symptoms scores of schizophrenia patients. The BDNF Met/Met patients had a higher score in negative symptoms and anxiety/depression symptoms compared with patients who is BDNF val/val and BDNF val/Met.4. Multiple linear regression analysis revealed that the Val66Met genotype together with gender and course explained approximately8.9%for the total PANSS scores. Be accompanied with gender, course and character type, the BDNF Val66Met genotype explained7.2%for the variance in negative symptoms. The BDNF Val66Met polymorphism by itself could explain approximately16%for the variance in anxiety/depression symptoms in schizophrenia patients.Conclusions1. Our data provides evidence that the BDNF Val66Met polymorphism may be involved in the etiology of schizophrenia in Han Chinese population and the Met allele may be a risk factor for schizophrenia.2. The BDNF Val66Met polymorphism is not associated with the gender, age, education years, family history, age onset, course and numbers of hospitalization of schizophrenia patients.3. The BDNF Val66Met polymorphism may has a genetic effect on the negative symptoms and anxiety/depression symptoms of schizophrenia patients.The BDNF Met/Met patients had more severe negative symptoms and anxiety/depression symptoms compared with patient who is BDNF Val/Val and BDNF val/Met.4. The BDNF Val66Met polymorphism is a significant influencing factor on the severity of anxiety/depression symptoms in schizophrenia patients.