title: Metabolic effects and the methylenetetrahydrofolate reductase (MTHFR) polymorphism associated with neural tube defects in southern Brazil.
abstract: BACKGROUND
  The importance of metabolic factors in neural tube defects (NTDs) has been the focus of many investigations. Several authors have suggested that abnormalities in homocysteine metabolism, such as hyperhomocysteinemia, folate deficiency, and low vitamin B12, may be responsible for these malformations and that both nutritional factors and genetic abnormalities are associated with them.
  
  
  METHODS
  We conducted a case-control study to investigate the influence of biochemical and genetic factors in NTDs in infants in southern Brazil. Levels of folate, vitamin B12, total homocysteine (t-Hcy) and the 677C>T and 1298A>C polymorphisms of the MTHFR gene were analyzed in 41 NTD child-mother pairs and 44 normal child-mother control pairs.
  
  
  RESULTS
  Subjects in the case group had a higher mean blood folate level than those in the control group. The level of vitamin B12 was lower in mothers in the NTD group than in control mothers (p = 0.004). The level of t-Hcy was not different in the two groups, but t-Hcy and vitamin B12 were correlated (p = 0.002). There was no difference in the genotype distribution for 677C>T and 1298A>C polymorphisms of MTHFR in the case and control pairs. The level of t-Hcy was correlated with 677TT.
  
  
  CONCLUSIONS
  Despite the small sample in this study, we suggest that low vitamin B12 and, consequently, hyperhomocysteinemia are important risk factors for NTDs in our population.
authors.affiliation: Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil. temis-feliz@uiowa.edu
authors.forename: Têmis Maria
authors.initials: TM
authors.lastname: Félix
authors.forename: Sandra
authors.initials: S
authors.lastname: Leistner
authors.forename: Roberto
authors.initials: R
authors.lastname: Giugliani
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007223:Infant; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics / Q000378:metabolism*; D009436:Neural Tube Defects / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D011110:Polymorphism, Genetic; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D014805:Vitamin B 12