Takenaka T, Shimomura T, Nakayasu H, Urakami K, Takahashi K
Division of Neurology, Faculty of Medicine, Tottori University.
Rinsho Shinkeigaku. 1993 Nov;33(11):1140-5.
Deficiency of 5,10-methylenetetrahydrofolate reductase (MTHFR) leads to deficient remethylation of homocysteine and is one of the causes of homocystinuria. Only 28 patients have been reported so far. A 15-year-old boy with mild mental retardation was admitted in our hospital because of progressive difficulty in walking. He is the second child. The paternal grandparents are first cousins. On admission, clinical examination revealed mild disturbance of consciousness, left hemiparesis, truncal ataxia, pyramidal tract signs in the lower limbs and sensory disturbance in his feet. There was no marfanoid symptoms nor ectopia lentis. EEGs showed slow activity with sporadic spike and wave complexes. Peak latencies of N20 of median nerves SEPs, the third and 5th wave of ABR and P100 of VEP were delayed. The CT scan showed mild cortical atrophy and MRI revealed increased intensity on T2-weighted images in the cerebral white matter. Biochemical studies revealed homocystinuria with homocystinemia. Both plasma methionine and serum folic acid were low. Serum vitamin B12 and methylmalonic acid in urine were normal. The lymphoblastoid cell line, transformed by Epstein-Barr virus of lymphocytes of the patient, could not grow when homocysteine was substituted in the culture medium for methionine. The normal control cell line grew naturally under the same condition. A diagnosis of homocystinuria due to MTHFR deficiency was made. The patient was on various therapeutic regimens for about 70 days. Treatment with high doses of folic acid (400 mg/day) resulted in disappearance of homocysteine in plasma, remarkable decrease of homocysteine in urine and increase of methionine in plasma of the patient.(ABSTRACT TRUNCATED AT 250 WORDS)
5,10-亚甲基四氢叶酸还原酶（MTHFR）缺乏会导致同型半胱氨酸再甲基化不足，是同型胱氨酸尿症的病因之一。迄今为止，仅报道过28例患者。一名15岁轻度智力发育迟缓男孩因进行性行走困难入院。他是家中第二个孩子。患儿的祖父母是近亲结婚。入院时，临床检查发现其存在轻度意识障碍、左侧偏瘫、躯干共济失调、下肢锥体束征及足部感觉障碍。无马方综合征样症状及晶状体异位。脑电图显示慢波活动伴散在棘波和复合波。正中神经体感诱发电位N20、听性脑干反应第3波及第5波和视觉诱发电位P100的峰潜伏期均延迟。CT扫描显示轻度皮质萎缩，MRI显示脑白质T2加权像信号增强。生化研究显示同型胱氨酸尿症伴同型半胱氨酸血症。血浆蛋氨酸和血清叶酸均降低。血清维生素B12及尿甲基丙二酸正常。用患者淋巴细胞经EB病毒转化的淋巴母细胞系，当培养基中用同型半胱氨酸替代蛋氨酸时不能生长。正常对照细胞系在相同条件下可自然生长。诊断为MTHFR缺乏所致同型胱氨酸尿症。该患者接受了约70天的各种治疗方案。大剂量叶酸（400mg/天）治疗后，患者血浆同型半胱氨酸消失，尿同型半胱氨酸显著减少，血浆蛋氨酸增加。（摘要截选至250词）
