Thermolabile variant of 5, 10-methylenetetrahydrofolate reductaseassociated with low red-cell folates: implications for folate intake recommendations

Autor:	James L. Mills, Alexander S. Whitehead, John M. Scott, Sean Daly, Anne M. Molloy, Dorothy Ramsbottom, Mary Conley, Peadar N. Kirke, Donald G. Weir
Rok vydání:	1997
Předmět:	Vitamin medicine.medical_specialty Genotype Population Biology 5 10-Methylenetetrahydrofolate Nutrition Policy chemistry.chemical_compound Folic Acid Pregnancy Internal medicine medicine Humans Prospective Studies Risk factor Thermolabile education Dietary Reference Values Methylenetetrahydrofolate Dehydrogenase (NADP) education.field_of_study Homozygote Genetic Variation General Medicine medicine.disease Diet Endocrinology chemistry Female
Zdroj:	The Lancet. 349:1591-1593
ISSN:	0140-6736
Popis:	Summary Background The dietary reference values for folate, as for other nutrients, are targeted to the general and supposedly normal population, not people with special needs, such as those with genetic or metabolic abnormalities or diseases. However, 5–15% of general populations are homozygous for a thermolabile variant of 5, 10-methylenetetrahydrofolate reductase (C677T) which causes mild hyperhomocysteinaemia and is positively associated with the development of vascular disease and the risk of neural-tube defects. If tissue-folate status is compromised in large sectors of the population by this or other genetic variants, the present dietary reference values may need to be changed. Methods We identified the C677T genotype and measured red-cell folate concentrations in two groups of healthy women (pregnant, 242, not pregnant, 318). We then analysed the effect of genotype on red-cell folates, which are a reliable marker for tissue folate stores. Findings In the pregnant group there were 20 TT homozygotes, 114 wild-type CC homozygotes, and 108 CT heterozygotes. In the non-pregnant group, the numbers were 41, 148, and 129. In both pregnant and non-pregnant groups, red-cell folate was significantly lower among TT homozygous than CC homozygous women (mean 252 [95% CI 202–317] vs 347 [321–372] μg/L, p=0·002 for pregnant women; 284 [250–327] vs 347 [342–372] μg/L, p=0·01 for non-pregnant women). Plasma folate was also significantly lower in TT homozygous than in CC homozygous women in the pregnant group (p=0·009) but not in the non-pregnant group. Interpretation These results suggest that a substantial minority of people in general populations may have increased folate needs. Future studies may show the presence of other common genetic variants that interact with particular nutrients and place doubts on the validity of assuming "normality" for nutrient requirements in any general population.
Databáze:	OpenAIRE
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