Study Report

Reference	Jonsson, E. G., 2008 PMID: 18165967
Citation	Jonsson, E. G., K. Larsson, et al. (2008). "Two methylenetetrahydrofolate reductase gene (MTHFR) polymorphisms, schizophrenia and bipolar disorder: an association study." Am J Med Genet B Neuropsychiatr Genet 147B(6): 976-982.
Disease Type	Bipolar Disorder & Schizophrenia
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	388 Danish diagnosed with schizophrenia or schizophreniform disorder, 31 Danish patients with schizoaffective disorder as well as 1,006 control subjects. 132 Norwegian patients with schizophrenia/schizophreniform disorder, 31 with schizoaffective disorder, 117 with bipolar disorder as well as 177 controls. In the Swedish sample there were 233 schizophrenic/schizophreniform and 25 schizoaffective patients as well as 293 controls.
SNP/Region/Marker Size	2 SNPs
Predominant Ethnicity	Caucasian
Population	Danish, Norwegian, Swedish
Gender	In the present study 388 Danish patients (58.2% men) diagnosed with schizophrenia or schizophreniform disorder and 31 patients (48.4% men) with schizoaffective disorder as well as 1,006 control subjects (58.4% men) were included. There were 132 Norwegian patients (60.6% men) diagnosed with schizophrenia/schizophreniform disorder, 31 with schizoaffective disorder (25.8% men) with bipolar disorder (39.3% men) as well as 177 controls (44.6% men). In the Swedish sample there were 233 schizophrenic/schizophreniform (62.7% men) and 25 schizoaffective patients (56.0% men) as well as 293 controls (62.5% men),
Age Group	adults : Danish patients mean age=44.4 (SD=12.2) years diagnosed with schizophrenia or schizophreniform disorder and 31 patients mean age=52.1 (SD=11.6) years with schizoaffective disorder as well as 1,006 control subjects, mean age = 44.2 (SD= 11.8) years were included. There were 132 Norwegian patients, mean age=36.6 (SD= 9.8) years diagnosed with schizophrenia/schizophreniform disorder, 31 with schizoaffective disorder, mean age=44.5 (SD=12.5) years, 117 with bipolar disorder, mean age= 41.0 (SD=12.2) years, as well as 177 controls, mean age=39.7 ( SD=10.3) years. In the Swedish sample there were 233 schizophrenic/schizophreniform, mean age=55.7 (SD=15.6) years and 25 schizoaffective patients,mean age=49.8 (SD=8.4)years as well as 293 controls, mean age=51.2 (SD=10.1) years.

Sample Diagnosis	DSM-III-R/DSM-IV; ICD-10
Technique	genotyping
Statistical Method	The allele and genotype frequencies among cases and controls were compared using contingency and 2 2 X2 tests. When 20% of the cells had an expected count<5, a Monte Carlo method was used [Sham and Curtis, 1995]. Odds ratios (OR), confidence intervals (CI), pooling of data and testing of heterogeneity between effect sizes were calculated with a fixed effect analysis according to Woolf [1955] as previously described
Result Summary	There were no statistically significant allele or genotype case-control differences. The present Scandinavian results do not verify previous associations between the putative functional MTHFR gene polymorphisms and schizophrenia or bipolar disorder. However, when combined with previous studies in meta-analyses there is still evidence for association between the MTHFR C677T polymorphism and schizophrenia.