There are 2 clinical trials
A genetic variation in the gene for the protein dihydrofolate reductase (DHFR) that is necessary to utilize folic acid (a synthetic form of the B vitamin folate found in supplements and fortified food), increases the risk for breast cancer in multivitamin users and, when present in mothers who used folic acid supplements during pregnancy, increases the risk for cancer of the eye of their children. The aim of the proposed research is to understand how a common genetic variation in the gene for DHFR affects the function of this protein and the ability of the body to use folic acid.
Characterize rs70991108 Polymorphism of DHFR Gene A 19bp deletion polymorphism of intron 1 of dihydrofolate reductase (DHFR 19bpdel) increases the risk for breast cancer, and retinoblastoma of the offspring, in folic acid supplement users.
Description: DHFR mRNA and protein abundance determined for the 19 bp deletion genotypes
Measure: DHFR mRNA and protein abundance Time: 1 yearDescription: Effect of DHFR 19bp deletion on reactions of folate pathway determined in cell culture conditions
Measure: Reactions of folate pathway Time: 1 yearIn this two-arm, double-blind randomized pilot study, the investigators will recruit 60 generally healthy, low-risk pregnant women aged 19-42 years living in Vancouver, Canada. Participants will be randomized to supplement with either 0.6 mg/day folic acid or an equimolar dose (0.625 mg/day) of (6S)-5-methyltetrahydrofolic acid for 16-weeks of their pregnancy. Randomization will occur at 8-21 weeks gestation (after neural tube closure) to reduce the risk of harm should the natural folate prove less effective. All participants will also receive a prenatal multivitamin not containing any form of folate, to ensure adequacy of other nutrients (e.g. iron) required during pregnancy. Three-hour fasting venous blood samples will be collected at baseline and endline to measure serum and red blood cell folate, unmetabolized folic acid and other related biomarkers. Women will be given the option to continue supplementing until 1-week postpartum, and provide a small (3mL) breastmilk sample in order to measure differences in folates in breastmilk. These pilot data will be used to inform a definitive trial regarding the most effective form of folate supplementation for mothers and their babies.
Gene variant assessment of MTHFR (677 C>T, rs1801133, and 1298 A>C, rs1801131) and DHFR (rs1643649 and rs70991108) and differences in DNA methylation.
Description: nmol/L; Reflects longer term status (e.g. previous 3-4 months)
Measure: Concentration of red blood cell folate levels Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: nmol/L; Reflects recent status or dietary intake
Measure: Concentration of serum folate levels Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: nmol/L; unmetabolized folic acid is not incorporated into RBCs, rather it circulates in plasma
Measure: Concentration of unmetabolized folic acid Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: pmol/mL; closely involved in folate metabolism and facilitating methionine cycles
Measure: Concentration of total vitamin B-12 Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: nmol/L; closely involved in folate metabolism and facilitating methionine cycles
Measure: Concentration of pyridoxal-5'-phosphate Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: µmol/L; closely involved in facilitating methionine cycles
Measure: Concentration of betaine Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: µmol/L; closely involved in facilitating methionine cycles
Measure: Concentration of choline Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: µM; Metabolite produced in methionine cycles
Measure: Concentration of S-adenosyl-methionine Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: µM; Metabolite produced in methionine cycles
Measure: Concentration of S-adenosyl-homocysteine Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: µmol/L; Metabolite produced in methionine cycles
Measure: Concentration of total homocysteine Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: µmol/L; Metabolite produced in methionine cycles
Measure: Concentration of methionine Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: µmol/L; Metabolite produced in methionine cycles
Measure: Concentration of cysteine Time: concentrations at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation), and calculation of change between time periodsDescription: Gene variant assessment of MTHFR (677 C>T, rs1801133, and 1298 A>C, rs1801131) and DHFR (rs1643649 and rs70991108) and differences in DNA methylation
Measure: Collection of peripheral blood mononuclear layer cells Time: Collection at both baseline (8-21 weeks gestation) and endline (24-37 weeks gestation)Description: nmol/L; folic acid that is unmetabolized and enters breastmilk as such
Measure: Concentration of unmetabolized folic acid in breastmilk Time: Collection at 1 week postpartumDescription: nmol folate binding per liter of milk
Measure: Folate binding protein in breastmilk Time: Collection at 1 week postpartum