title: Preliminary evidence for genetic selection of 677T-MTHFR by natural annual cycle of folate abundance.
abstract: OBJECTIVE
  Folic acid mediates transfer of one-carbon units into methionine and DNA-thymine biosynthesis. Discretionary and mandatory use of synthetic folic acid (SFA) to reduce spina bifida is on the increase. We show that historically, the seasonal cycle of abundance of folate-rich foods may have regulated embryo viability by acting as a selection factor for a significant polymorphism within a gene encoding 5,10-methylenetetrahydrofolate reductase (677C-->T-MTHFR).
  
  
  METHODS
  Blood was collected from 150 UK and 118 Australian subjects born prior to discretionary or mandatory use of SFA. 677C-->T-MTHFR genotype was determined using PCR.
  
  
  RESULTS
  The highest prevalence for 677T-MTHFR occurred 9 months post-harvest in UK subjects and was significantly higher at this time of year (July-Sept.) compared with Jan.-Mar. (OR = 2.0, 95% CI 1.03-3.87, p = 0.039) and Oct.-Dec. (OR = 2.2, 95% CI 1.12-4.31, p = 0.021). This effect was not detected in an Australian population subject to more moderate seasonality.
  
  
  CONCLUSIONS
  Dietary folate may confer significant genetic buffering within populations dependent upon seasonal food sources that modify an individual's vitamin status at the time of conception.
authors.affiliation: School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW 2258, Australia. Mark.Lucock@newcastle.edu
authors.forename: Mark
authors.initials: M
authors.lastname: Lucock
authors.forename: Zoë
authors.initials: Z
authors.lastname: Yates
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Ng
authors.forename: Martin
authors.initials: M
authors.lastname: Veysey
authors.forename: Barbara
authors.initials: B
authors.lastname: Blades
authors.forename: Cheryl
authors.initials: C
authors.lastname: Travers
authors.forename: Peter
authors.initials: P
authors.lastname: Lewis
authors.forename: Jonathon
authors.initials: J
authors.lastname: Sturm
authors.forename: Paul
authors.initials: P
authors.lastname: Roach
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012641:Selection, Genetic
chemical_list: D017931:DNA Primers; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2)