[An adult case of homocystinuria probably due to methylenetetrahydrofolate-reductase deficiency--treatment with folic acid and the course of coagulation-fibrinolysis parameters].

We report a rare male case of homocystinuria probably due to methylenetetrahydrofolate-reductase deficiency. The onset of his disorder was at 19 years of age, and he had no family history. He initially developed gait disturbance, and then generalized seizure in several months, which made him admitted to our hospital. Neurological examinations revealed mental dysfunction, spastic paraplegia, cerebellar ataxia, and sensory disturbance in his feet. MRI showed multiple increased intensities on T2-weighted images in the cerebral white matter. EMG revealed neurogenic changes. These symptoms and signs slowly progressed, and he then developed thrombophlebitis in his lower extremities. Thrombin-antithrombin III complex (TAT) and D-dimer remained high continuously, and plasma homocysteine level was more than ten times higher than the normal range. Plasma cystathionine level was high and methionine level was low. The serum folic acid, vitamin B12, and methylmalonic acid in the urine were normal. Megaloblastic anemia was not seen. Based on these data, he was diagnosed to have homocystinuria probably due to methylenetetrahydrofolate-reductase deficiency. Treatment with high doses of folic acid, pyridoxine and cobalamin normalized plasma cystathionine and methionine levels, and markedly decreased plasma homocysteine, although it remained about three times higher than the normal range. Thereafter, both TAT and D-dimer levels also markedly decreased. The administration of folic acid reduced elevated plasma homocysteine as well as the coagulation--fibrinolysis factors. This implies that they may serve as useful markers for effective treatment of this disease.