Study Report

Reference	Skibinska, M., 2004 PMID: 15543516
Citation	Skibinska, M., J. Hauser, et al. (2004). "Association analysis of brain-derived neurotrophic factor (BDNF) gene Val66Met polymorphism in schizophrenia and bipolar affective disorder." World J Biol Psychiatry 5(4): 215-220.
Disease Type	Bipolar Disorder & Schizophrenia
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	336 patients with schizophrenia, 352 patients with bipolar affective disorder and 375 controls
SNP/Region/Marker Size	1 polymorphism
Predominant Ethnicity	Caucasian
Population	Polack
Gender	189 males and 147 females with schizophrenia, 128 males and 172 females with bipolar I affective disorder, 18 males and 34 females with bipolar II affective disorder; 149 male and 226 female controls
Age Group	adults : 189 males with a mean age of 30.6 years, SD=11.3, 147 females with a mean age of 33.2 years, SD=12.1 of patients with schizophrenia; 128 males with a mean age of 45.1 years, SD=14.5; 172 females with a mean age of 47.5 years, SD=13.6 of patients with bipolar I affective disorder; 18 males with a mean age of 44.0 years, SD=12.8; 34 females with a mean age of 43.5 years, SD=14.3 of patients with bipolar II affective disorder; 149 males with a mean age of 41.2 years, SD=120; 226 females with a mean age of 40.4 years, SD=10.8 of controls

Sample Diagnosis	DSM-IV and ICD-10
Sample Status	Patients were recruited from inpatients being treated at the Department of Psychiatry, University of Medical Sciences in Poznan, Department of Psychiatry, University School of Medicine in Bydgoszcz and Psychiatric Hospital in Koscian. 300 patients with bipolar I affective disorder, 52 patients with bipolar II affective disorder.
Technique	genotyping
Statistical Method	The Pearson's chi-square (_2) test and Fisher's exact test were applied to test differences in the genotypic and allelic (respectively) distribution between groups of bipolar patients, schizophrenic patients and controls. Additionally, stepwise logistic regression analyses for each diagnostic group including BDNF polymorphism, age and gender as covariates were performed.
Result Summary	No association was found between the studied polymorphism and schizophrenia or bipolar affective disorder either for genotype or allele distribution (for genotype: p=0.210 in schizophrenia, p=0.400 in bipolar disorder; for alleles: p=0.260 in schizophrenia, p=0.406 in bipolar disorder). Results were also not significant when analysed by gender. For males genotype distribution and allele frequency were (respectively): p=0.480 and p=0.312 in schizophrenia, p=0.819 and p=0.673 in bipolar affective disorder. Genotype distribution and allele frequency observed in the female group were: p=0.258 for genotypes, p=0.482 for alleles in schizophrenia; p=0.432 for genotypes, p=0.464 for alleles in bipolar affective disorder. A subgroup of schizophrenic (n=62) and bipolar affective patients (n=28) with early age at onset (18 years or younger) was analysed (p=0.328 for genotypes, p=0.253 for alleles in schizophrenia; p=0.032 for genotypes, p=0.858 for alleles in bipolar affective disorder).