Common mutation in methylenetetrahydrofolate reductase : Correlation with homocysteine metabolism and late-onset vascular disease

• Published in: Circulation (New York, N.Y.) Vol. 94; no. 12; pp. 3074 - 3078
• Main Authors: DELOUGHERY, T. G, EVANS, A, SADEGHI, A, MCWILLIAMS, J, HENNER, W. D, TAYLOR, L. M, PRESS, R. D
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 15.12.1996; American Heart Association, Inc
• Subjects: Adult; Age of Onset; Aged; Atherosclerosis (general aspects, experimental research); Base Sequence; Biological and medical sciences; Blood and lymphatic vessels; Blood Donors; Canada; Cardiology. Vascular system; DNA Primers; Gene Frequency; Genotype; Homocysteine - metabolism; Homozygote; Humans; Infant, Newborn; Medical sciences; Methylenetetrahydrofolate Reductase (NADPH2); Middle Aged; Oxidoreductases Acting on CH-NH Group Donors - genetics; Point Mutation; Polymerase Chain Reaction; Reference Values; Regression Analysis; Vascular Diseases - genetics; Vascular Diseases - physiopathology; Canada; Vascular disease; Human; Methylenetetrahydrofolate reductase (NADPH); Enzyme; Atherosclerosis; Risk factor; Cardiovascular disease; Exploration; Oxidoreductases; Mutation; Metabolism
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.94.12.3074

Increased homocysteine levels are a risk factor for atherosclerosis and its sequelae. A common genetic mutation in methylenetetrahydrofolate reductase (MTHFR), an enzyme required for efficient homocysteine metabolism, creates a thermolabile enzyme with reduced activity. We determined the prevalence of this mutation in many subjects with and without vascular disease and related it to homocysteine and folate levels. DNA from 247 older subjects with vascular disease and 594 healthy subjects without vascular disease (in three different control groups) was screened for the MTHFR 677 C-to-T mutation. Within each group, 9% to 17% of the subjects were homozygous for this mutation, and the mutant allele frequency was 31% to 39%. The genotype distributions, homozygote frequencies, and allele frequencies did not differ significantly between the study groups. In the vascular disease subjects, despite significantly lower folate levels in MTHFR homozygotes, there was no significant difference in homocysteine levels among the MTHFR genotype groups. The negative slope of the regression line relating homocysteine and folate was significantly steeper for those with a homozygous MTHFR mutation compared with those without this mutation. Although the thermolabile MTHFR mutation is very common, it does not appear to be a significant genetic risk factor for typical late-onset vascular disease. Because MTHFR homozygotes have increased homocysteine with low folate levels, this mutation may contribute to early-onset or familial vascular disease. The genotype dependence of the folate-homocysteine correlation further suggests that homozygotes for this mutation may have both an exaggerated hyperhomocysteinemic response to folic acid depletion and a better response to folic acid therapy.