A COMMON MUTATION IN METHYLENETETRAHYDROFOLATE REDUCTASE GENE AMONG THE JAPANESE POPULATION

Hyperhomocysteinemia has been reported as an independent risk factor f or atherosclerotic cerebrovascular and coronary heart diseases. 5,10-M ethylenetetrahydrofolate reductase (MTHFR) is one of the enzymes respo nsible for hyperhomocysteinemia. The C to T transition of the MTHFR ge ne at nucleotide position 677 results in decreasing the enzymatic acti vity and increasing the plasma homocysteine level. We studied the dist ribution of the MTHFR gene mutation among the Japanese population. The subjects were 129 Japanese males (aged 40-59 years). The allele frequ ency of the mutation was 0.38, The frequencies of the three genotypes were as follows: +/+, 11%; +/-, 54%; -/-, 35% (+ and - indicate the pr esence and absence of the mutation, respectively). We also studied the frequency of the MTHFR gene mutation in the middle-aged Japanese male s with hypertension to investigate the possibility that this mutation is related to essential hypertension. The normotensive and hypertensiv e subjects were identical in the distribution of the mutated allele an d the frequencies of the three genotypes. Furthermore, the prevalence of hypertension in each genotype group was same, although the mean dia stolic pressure of the group with homozygous mutation was significantl y higher than that of other groups (p<0.05).