Preliminary evidence for genetic selection of 677T-MTHFR by natural annual cycle of folate abundance.
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.
Lucock
Mark
M
School of Environmental and Life Sciences, University of Newcastle, Ourimbah, NSW 2258, Australia. Mark.Lucock@newcastle.edu
Yates
Zoë
Z
Ng
Xiaowei
X
Veysey
Martin
M
Blades
Barbara
B
Travers
Cheryl
C
Lewis
Peter
P
Sturm
Jonathon
J
Roach
Paul
P
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
D017931:DNA Primers; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2)