Stöckler S, Hanefeld F
Universitätsklinik für Kinder- und Jugendheilkunde, Wien, Osterreich.
Wien Klin Wochenschr. 1997 Feb 14;109(3):86-8.
In an infant with progressive, severe extrapyramidal movement disorder and extremely. low urinary creatinine excretion, in vivo proton magnetic resonance spectroscopy of the brain showed a depletion of creatine and an accumulation of guanidinoacetate, the immediate precursor of creatine. The suggested defect in creatine biosynthesis at the level of guanidinoacetate methyltransferase was confirmed by the demonstration of defective activity of this enzyme in liver tissue and by identification of the underlying genetic defect. Creatine substitution by means of oral creatine monohydrate at high dosage (4-8 g per day) resulted in a striking improvement of the extrapyramidal movement disorder, normalisation of abnormal slow background activity in the EEG, and disappearance of bilateral abnormal signal intensities in the globus pallidus. The low urinary creatine excretion normalized and brain creatine and creatine phosphate, as measured by in vivo magnetic resonance spectroscopy, increased significantly. Guanidinoacetate methyltransferase deficiency is a new, treatable inborn error of metabolism. Screening methods and non-invasive diagnosis of the enzyme defect are needed for the early detection and treatment of patients with this effect.
在一名患有进行性严重锥体外系运动障碍且尿肌酐排泄极低的婴儿中，脑部的活体质子磁共振波谱显示肌酸耗竭以及胍基乙酸（肌酸的直接前体）蓄积。通过证明肝组织中该酶活性缺陷以及鉴定潜在的基因缺陷，证实了在胍基乙酸甲基转移酶水平上肌酸生物合成存在缺陷。通过口服高剂量（每天4 - 8克）一水肌酸进行肌酸替代治疗，导致锥体外系运动障碍显著改善、脑电图中异常慢背景活动恢复正常以及苍白球双侧异常信号强度消失。尿肌酸排泄量低的情况恢复正常，通过活体磁共振波谱测量，脑内肌酸和磷酸肌酸显著增加。胍基乙酸甲基转移酶缺乏是一种新的、可治疗的先天性代谢缺陷。需要筛查方法和该酶缺陷的非侵入性诊断方法，以便对患有这种病症的患者进行早期检测和治疗。
