The influence of 5,10 methylenetetrahydrofolate reductase genotypes on enzyme activity in placental tissue.
Level 4 - case-series / case-control
Cross-sectional observational tissue study measuring enzyme activity across genotypes.
PubMed 10549970 · doi:10.1111/j.1471-0528.1999.tb08151.x
What was done
Placental tissue samples (n = 200) from uncomplicated term deliveries at a single teaching hospital were genotyped for the MTHFR C677T mutation. Total MTHFR enzyme activity and residual enzyme activity after heating to 46°C for 5 minutes were measured and compared across genotypes in pregnancies unaffected by neural tube defects.
What was found
Placentae heterozygous for the MTHFR C677T mutation had significantly lower total enzyme activity than wild-type samples, with homozygous mutant tissues showing the lowest activity. The same stepwise reduction was observed for residual enzyme activity after heating. No specific numerical values, variances, or p-values were provided in the abstract.
Why it matters
This study confirms in human placental tissue that the C677T variant impairs baseline and heat-stable MTHFR enzyme activity, supporting a biological mechanism for altered folate metabolism during gestation.
Limits
The abstract provides no numerical measurements, effect estimates, or significance levels. Findings are restricted to healthy, term pregnancies unaffected by neural tube defects, and maternal genotype or circulating folate/homocysteine levels were not reported.
Cited by
- supports A homozygous MTHFR polymorphism reduces the MTHFR enzyme's efficiency to roughly 10% to 20% of normal function.