title: Prevalence of methylenetetrahydrofolate reductase 677T and 1298C alleles and folate status: a comparative study in Mexican, West African, and European populations.
abstract: BACKGROUND
  Methylenetetrahydrofolate reductase (MTHFR) 677C-->T polymorphism is heterogeneously distributed worldwide, with the highest and lowest frequencies of the T allele in Mexico and Africa, respectively, and a south-to-north gradient in Europe. Distribution of MTHFR 1298A-->C is less well known. It has been hypothesized that 677T frequency could result in part from gene-nutrient interactions.
  
  
  OBJECTIVE
  The objective was to compare the association of 677T and 1298C alleles with plasma concentrations of homocysteine, folate, and vitamin B-12 in geographical areas with contrasting 677T allele frequencies.
  
  
  METHODS
  Healthy young adults (n = 1277) were recruited in Mexico City, the West African countries of Bénin and Togo, France, and Sicily (Italy). Homocysteine, folate, and vitamin B-12 were measured in plasma, and MTHFR polymorphisms were measured in genomic DNA.
  
  
  RESULTS
  Mexico City and Sicily reported the highest and Bénin and Togo reported the lowest plasma concentrations of folate. Mexico City had the highest 677T allele prevalence and the lowest influence of 677TT genotype on homocysteine, whereas the opposite was observed in Africa. The prevalence of the 1298C allele was lowest in the Mexicans and Africans and highest in the French. The percentage of the 677T genotype was significantly associated with the folate concentrations in 677CC carriers in a univariate analysis (R = 0.976; 95% CI: 0.797, 0.996; P < 0.0002) and in a multiple regression model that included homocysteine, vitamin B-12, and age (P = 0.0002).
  
  
  CONCLUSIONS
  Our data agree with the hypothesis of a gene-nutrient interaction between MTHFR 677C-->T polymorphism and folate status that may confer a selective advantage of TT-homozygous genotype when dietary intake of folate is adequate, at least in the areas studied.
authors.affiliation: INSERM U-724, Cellular and Molecular Pathology in Nutrition, Faculté de Médecine, University Henry Poincaré of Nancy, Vandoeuvre lès Nancy, France.
authors.forename: Rosa-Maria
authors.initials: RM
authors.lastname: Guéant-Rodriguez
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Guéant
authors.forename: Renée
authors.initials: R
authors.lastname: Debard
authors.forename: Sylvie
authors.initials: S
authors.lastname: Thirion
authors.forename: Lu Xiao
authors.initials: LX
authors.lastname: Hong
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bronowicki
authors.forename: Farès
authors.initials: F
authors.lastname: Namour
authors.forename: Nicodème W
authors.initials: NW
authors.lastname: Chabi
authors.forename: Ambaliou
authors.initials: A
authors.lastname: Sanni
authors.forename: Guido
authors.initials: G
authors.lastname: Anello
authors.forename: Paolo
authors.initials: P
authors.lastname: Bosco
authors.forename: Corrado
authors.initials: C
authors.lastname: Romano
authors.forename: Emile
authors.initials: E
authors.lastname: Amouzou
authors.forename: Heidy R
authors.initials: HR
authors.lastname: Arrieta
authors.forename: Beatríz E
authors.initials: BE
authors.lastname: Sánchez
authors.forename: Antonino
authors.initials: A
authors.lastname: Romano
authors.forename: Bernard
authors.initials: B
authors.lastname: Herbeth
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Guilland
authors.forename: Osvaldo M
authors.initials: OM
authors.lastname: Mutchinick
mesh_terms: D000293:Adolescent; D000328:Adult; D000354:Africa, Western; D000483:Alleles; D005060:Europe; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005787:Gene Frequency; D005838:Genotype; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008800:Mexico; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012044:Regression Analysis; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D014805:Vitamin B 12