Genetic polymorphism of 5,10-methylenetetrahydrofolate increases risk of myocardial infarction and is correlated to elevated levels of homocysteine in the Japanese general population.
BACKGROUND
Hyperhomocysteinemia, an independent and graded risk factor for coronary artery disease, can result from both environmental and hereditary factors. C677T mutation of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene [alanine/valine (A/V) polymorphism], one of the key enzymes involved in catalyzing the remethylation of homocysteine, has recently been reported.


OBJECTIVE
To evaluate the incidence of the MTHFR genotypes and their significance in determining the risk for myocardial infarction of Japanese men.


METHODS
The subjects consisted of 199 healthy men (mean age, 60 years) and 230 male patients with myocardial infarction (mean age, 59 years). The coronary-artery lesions were evaluated by coronary angiography. The MTHFR genotype was analyzed by polymerase chain reaction and then by digestion with Hinfl. Total plasma levels of homocysteine for each MTHFR genotype were compared with those in healthy controls.


RESULTS
The prevalences of the A and V alleles among the healthy male subjects were 0.652 and 0.348 in the Hardy-Weinberg equilibrium. The total levels of homocysteine in the plasma of the healthy male subjects were 8.6 +/- 3.3, 8.9 +/- 4.1, and 11.6 +/- 5.6 mumol/l, for AA, AV, and VV genotypes, respectively. Individuals with the VV homozygous mutant genotype thus had the highest plasma levels of homocysteine. Logistic analysis revealed that the levels of high-density lipoprotein cholesterol, hypertension, diabetes mellitus, MTHFR VV genotype, and triglycerides were all independent risk factors for myocardial infarction. The VV genotype was more prevalent among patients with myocardial infarction (mean age, 59 years) than it was among the control subjects (17.0 versus 10.6%, P < 0.05). However, there were no differences in the numbers of stenotic coronary arteries among the MTHFR genotypes.


CONCLUSIONS
The VV genotype of MTHFR increases plasma levels of homocysteine in healthy controls, and this mutation indicates a genetic predisposition toward a greater than normal risk of myocardial infarction for Japanese men.
Nakai
K
K
Second Department of Internal Medicine & Memorial Heart Center, Iwate Medical University, Tokyo, Japan. knakai@iwate-med.ac.jp
Fusazaki
T
T
Suzuki
T
T
Ohsawa
M
M
Ogiu
N
N
Kamata
J
J
Kawazoe
K
K
Nakai
K
K
Itoh
C
C
Yanagisawa
M
M
Ishida
T
T
Hiramori
K
K
D015331:Cohort Studies; D006710:Homocysteine / Q000009:adverse effects / Q000097:blood*; D006801:Humans; D007564:Japan; D008297:Male; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP) / Q000235:genetics*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000235:genetics* / Q000517:prevention & control; D016133:Polymerase Chain Reaction; D012307:Risk Factors; D014815:Vitamins / Q000627:therapeutic use
D014815:Vitamins; D006710:Homocysteine; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP)