No association of the brain-derived neurotrophic factor (BDNF) gene C-270T polymorphism with schizophrenia

Brain-derived neurotrophic factor (BDNF) regulates a variety of neuromodulatory processes during development, as well as in adulthood. It has been proposed as a risk factor for schizophrenia. We have investigated a possible association between schizophrenia and the C-270T polymorphism in the brain-derived neurotrophic factor (BDNF) gene in 397 schizophrenic patients and 380 control subjects. The diagnosis of schizophrenia was made for each patient by at least two psychiatrists, using DSM-IV and ICD-10 criteria in structured clinical interviews for DSM-IV Axis I disorders (SCID). No association was found between schizophrenia and the analyzed polymorphism, for either genotype or allele distribution (for genotype: p = 0.513, for alleles: p = 0.812). Differences were not statistically significant when analyzed separately by sex. For males, the differences for genotype distribution and allele frequency were p = 0.078 and p = 0.162 respectively and for females: p = 0.441 and p = 0.315. Thus, our data indicate that variations in the BDNF gene are unlikely to be an important factor in susceptibility to schizophrenia.