title: Association between decreased vitamin levels and MTHFR, MTR and MTRR gene polymorphisms as determinants for elevated total homocysteine concentrations in pregnant women.
abstract: OBJECTIVE
  To examine the association between methylenetetrahydrofolate reductase (MTHFR) (C677T and A1298C), methionine synthase (MTR) A2756G and methionine synthase reductase (MTRR) A66G gene polymorphisms and total homocysteine (tHcy), methylmalonic acid (MMA) and S-adenosylmethionine/S-adenosylhomocysteine (SAM/SAH) levels; and to evaluate the potential interactions with folate or cobalamin (Cbl) status.
  
  
  METHODS
  Two hundred seventy-five healthy women at labor who delivered full-term normal babies. Cbl, folate, tHcy, MMA, SAM and SAH were measured in serum specimens. The genotypes for polymorphisms were determined by PCR-restriction fragment length polymorphism (RFLP).
  
  
  RESULTS
  Serum folate, MTHFR 677T allele and MTR 2756AA genotypes were the predictors of tHcy levels in pregnant women. Serum Cbl and creatinine were the predictors of SAM/SAH ratio and MMA levels, respectively. The gene polymorphisms were not determinants for MMA levels and SAM/SAH ratios. Low levels of serum folate were associated with elevated tHcy in pregnant women, independently of the gene polymorphisms. In pregnant women carrying MTHFR 677T allele, or MTHFR 1298AA or MTRR 66AA genotypes, lower Cbl levels were associated with higher levels of tHcy. Lower SAM/SAH ratio was found in MTHFR 677CC or MTRR A2756AA genotypes carriers when Cbl levels were lower than 142 pmol/l.
  
  
  CONCLUSIONS
  Serum folate and MTHFR C677T and MTR A2576G gene polymorphisms were the determinants for tHcy levels. The interaction between low levels of serum Cbl and MTHFR (C677T or A1298C) or MTRR A66G gene polymorphisms was associated with increased tHcy.
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas da Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: P R
authors.initials: PR
authors.lastname: Barbosa
authors.forename: S P
authors.initials: SP
authors.lastname: Stabler
authors.forename: A L K
authors.initials: AL
authors.lastname: Machado
authors.forename: R C
authors.initials: RC
authors.lastname: Braga
authors.forename: R D C
authors.initials: RD
authors.lastname: Hirata
authors.forename: M H
authors.initials: MH
authors.lastname: Hirata
authors.forename: L F
authors.initials: LF
authors.lastname: Sampaio-Neto
authors.forename: R H
authors.initials: RH
authors.lastname: Allen
authors.forename: E M
authors.initials: EM
authors.lastname: Guerra-Shinohara
mesh_terms: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000483:Alleles; D000704:Analysis of Variance; D005260:Female; D005287:Ferredoxin-NADP Reductase / Q000235:genetics*; D005492:Folic Acid / Q000097:blood; D005787:Gene Frequency; D005838:Genotype; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008764:Methylmalonic Acid / Q000097:blood; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011247:Pregnancy / Q000097:blood* / Q000235:genetics; D012435:S-Adenosylhomocysteine / Q000097:blood; D012436:S-Adenosylmethionine / Q000097:blood; D014805:Vitamin B 12 / Q000097:blood; D055815:Young Adult
chemical_list: D006710:Homocysteine; D012436:S-Adenosylmethionine; D008764:Methylmalonic Acid; D005492:Folic Acid; D012435:S-Adenosylhomocysteine; C111241:methionine synthase reductase; D005287:Ferredoxin-NADP Reductase; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D014805:Vitamin B 12