title: Genetic analysis of the thermolabile methylenetetrahydrofolate reductase variant in schizophrenia and mood disorders.
abstract: OBJECTIVE
  An elevated homocysteine level has been reported for patients with schizophrenia and depression. We investigated the frequency of the common C667 T variant of the enzyme methylenetetrahydrofolate reductase in controls and patients of Chinese descent.
  
  
  METHODS
  Controls with no history of mental disorder and patients diagnosed with schizophrenia, bipolar and unipolar disorders were recruited. Genomic DNA from all were genotyped for the C667 T polymorphism by polymerase chain reaction-restriction fragment length polymorphism.
  
  
  RESULTS
  There was no significant difference in genotype distributions or allele frequencies between controls and any of the diagnostic groups, although the frequency of the T allele was higher for all diagnostic groups and for both the male and female genders. When data was analyzed with the minor T allele as dominant, there was an excess of the T-containing genotypes in each of the patient groups compared with controls. For the difference between controls and all cases combined it almost reached statistical significance (P=0.077), with an odds ratio of 1.46 (95% confidence interval, 0.96-2.22).
  
  
  CONCLUSIONS
  Although there was no significant association as measured by the P value, the odds ratio and confidence interval provided some evidence of increased risk for individuals with the T-containing genotypes. A minor role for this polymorphism in the pathogenesis of schizophrenia and depression could not be ruled out and would warrant further investigation.
authors.affiliation: Defence Medical Research Institute, Defence Science and Technology Agency, Republic of Singapore. tenechoo@dso.org.sg
authors.forename: Ene-Choo
authors.initials: EC
authors.lastname: Tan
authors.forename: Siow-Ann
authors.initials: SA
authors.lastname: Chong
authors.forename: Lionel C C
authors.initials: LC
authors.lastname: Lim
authors.forename: Angelina O M
authors.initials: AO
authors.lastname: Chan
authors.forename: Yik-Ying
authors.initials: YY
authors.lastname: Teo
authors.forename: Chay-Hoon
authors.initials: CH
authors.lastname: Tan
authors.forename: Rathi
authors.initials: R
authors.lastname: Mahendran
mesh_terms: D000328:Adult; D000483:Alleles; D003596:Cytosine; D004247:DNA / Q000097:blood / Q000235:genetics / Q000302:isolation & purification; D003710:Demography; D003866:Depressive Disorder / Q000201:enzymology / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D019964:Mood Disorders / Q000201:enzymology / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012016:Reference Values; D012559:Schizophrenia / Q000201:enzymology / Q000235:genetics*; D013941:Thymine
chemical_list: D003596:Cytosine; D004247:DNA; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D013941:Thymine