title: Low ratio of S-adenosylmethionine to S-adenosylhomocysteine is associated with vitamin deficiency in Brazilian pregnant women and newborns.
abstract: BACKGROUND
  Pregnant women with low cobalamin concentrations are unable to provide the necessary amount of cobalamin to their fetuses. The effect of low maternal cobalamin concentrations on transmethylation metabolism in pregnant women and their newborns is unknown.
  
  
  OBJECTIVE
  We investigated the relation between maternal and neonatal cobalamin concentrations and changes in total homocysteine (tHcy), S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH).
  
  
  METHODS
  Hematologic data and concentrations of cobalamin, red blood cell folate, serum folate, tHcy, methylmalonic acid, SAM, SAH, and other metabolites were measured in 119 serum specimens from pregnant Brazilian women (gestational age: 37-42 wk) and their newborns' placental veins at the time of delivery.
  
  
  RESULTS
  The tHcy concentrations were higher in placental vein serum from newborns whose mothers had low cobalamin. Serum SAH concentrations were elevated and serum SAM and methionine concentrations were decreased in pregnant women with lower cobalamin concentrations. SAM:SAH was significantly decreased in both cobalamin-deficient pregnant women and their newborns.
  
  
  CONCLUSIONS
  Lower maternal cobalamin concentrations are associated with higher tHcy and lower SAM:SAH in newborns. Because SAM:SAH is closely linked with the activity of numerous enzymatic methylation reactions, these results suggest that methylation could be impaired in cobalamin-deficient pregnant women and their newborns.
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas da Universidade de São Paulo, São Paulo, Brazil. emguerra@usp.br
authors.forename: Elvira M
authors.initials: EM
authors.lastname: Guerra-Shinohara
authors.forename: Olga E
authors.initials: OE
authors.lastname: Morita
authors.forename: Sabrina
authors.initials: S
authors.lastname: Peres
authors.forename: Regina A
authors.initials: RA
authors.lastname: Pagliusi
authors.forename: Luiz F
authors.initials: LF
authors.lastname: Sampaio Neto
authors.forename: Vânia
authors.initials: V
authors.lastname: D'Almeida
authors.forename: Silvia P
authors.initials: SP
authors.lastname: Irazusta
authors.forename: Robert H
authors.initials: RH
authors.lastname: Allen
authors.forename: Sally P
authors.initials: SP
authors.lastname: Stabler
mesh_terms: D000328:Adult; D001724:Birth Weight; D001938:Brazil / Q000453:epidemiology; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005865:Gestational Age; D006710:Homocysteine / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D012372:ROC Curve; D012435:S-Adenosylhomocysteine / Q000097:blood*; D012436:S-Adenosylmethionine / Q000097:blood*; D012923:Social Class; D014806:Vitamin B 12 Deficiency / Q000097:blood* / Q000453:epidemiology
chemical_list: D006710:Homocysteine; D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine