Moderate hyperhomocysteinemia is an independent risk factor for thrombotic vascular disease. A C677T substitution of the MTHFR gene has been reported as the leading cause of moderate hyperhomocysteinemia. We have evaluated the frequency of the C677T mutation of the MTHFR gene in 64 unrelated young thrombophilic patients. In 29 (16 men, 13 women, 37.6±13.8 yrs old, 7 with arterial and 22 with venous thrombosis) fasting total plasma homocysteine was above the 95th percentile of the distribution (19.5 mM in men and 15 mM in women). These patients were matched for sex, age, type of event and age at first thrombotic event with the other 35. In all cases, nutrient-related disturbances of vitamin B12 and folate and abnormalities of cystathionine b-synthase enzyme were excluded. Normal subjects (258) free of vascular disease served as controls. Homozygosity for the C677T mutation (+/+) was found in 15% of controls (95%C.I.=11-20%). Among the 35% patients with normal homocysteinemia, one only was homozygous for the mutation. In contrast the +/+ genotype was found in 18/29 (62%) of those with hyperhomocysteinemia (9 men, 9 women, 5 with arterial and 13 with venous thrombosis). Plasma homocystein was not significantly different in the 18 patients homozygous for the mutation (32±19 mM) and in the remaining 11 hyperhomocysteinemic patients (23±5 mM, p>0.01). These results indicate that in young thrombophilic patients homozygosity for the C677T mutation of the MTHFR gene is the prevalent cause of moderate fasting hyperhomocysteinemia. These data also suggest that in a high proportion of these thrombophilic patients, factors other than C677T mutations are responsible for moderate hyperhomocysteinemia.
|Number of pages||1|
|Issue number||SUPPL. 1|
|Publication status||Published - 1996|
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