儿童运动及智能障碍者四氢生物蝶呤代谢病筛查及基因研究

Screening for tetrahydrobiopterin metabolic disorders and related gene analysis among the patients with motor disturbance and mental retardation

目的探讨四氢生物蝶呤（tetrahydrobiopterin，BH4）代谢中各酶缺乏在儿童运动及智能发育障碍者中发生率及基因突变。方法对100例运动及智能障碍患者进行苯丙氨酸（phenylalanine，Phe）及BH4负荷试验、尿蝶呤谱分析、红细胞二氢蝶啶还原酶测定，并对部分患者进行多巴治疗性诊断；对诊断为多巴反应性肌张力障碍（dopa-responsive dystonia，DRD）及6-丙酮酰四氢蝶呤合成酶（6-pyruvoyl tetrahydropterin synthase，PTS）缺乏者做基因突变检测。结果100例中70例基础血Phe浓度正常，6例（6％）诊断为DRD；30例有高苯丙氨酸血症[Phe（1022±290）μmol／L]，8例（8％）诊断为VIS缺乏症，22例（22％）诊断为苯丙氨酸羟化酶缺乏症。发现2例DRD患者其三磷酸鸟苷环化酶基因（GTP cyclohydrolase 1 gene，GCHI）突变为IVS5＋3insT，8例FIS缺乏症患者存在PTS基因7种突变类型，其中259C→T，286G→A，155A→G最常见，占75％。结论一些肌张力障碍或智能障碍者是由于BH4代谢障碍所致，有必要做筛查诊断以明确诊断。

Objective To study the incidence of various enzyme deficiency in tetrahydrobiopterin （BH4） metabolism and the related gene mutation among the patients with motor disturbance and mental retardation. Methods One hundred patients with unknown motor disturbance and mental retardation were referred to this study. All patients were performed by phenylalanine （Phe） and BH4 loading test, urinary pterin analysis and dihydropteridine reductase （DHPR） activity. Some patients received the dopa treatment for diagnosis of dopa-responsive dystonia （DRD）. The analysis of GTP cyclohydrolase 1 gene （C, CH1） mutation for DRD patients and the analysis of 6-pyruvoyl tetrahydropterin synthase （PTS） gene mutations for PTS deficient patients were done under the consent from their parents. Results Seventy of 100 patients had normal basic blood Phe levels, six （6%） patients were diagnosed as DRD. Thirty patients had hyperphenylalaninemia （HPA）, eight （8%） were diagnosed as PTS deficiency and 22（22%） were diagnosed as phenylalanine hydroxylase （PAH） deficiency. All patients had normal DHPR activity. The mutation 1VS5 ＋ 3iusT of C, CH1 was found in 2 patients with DRD. Seven kinds of PTS mutations were found in 8 patients with PTS deficiency, and 75% of the mutations were 259C→T,286G→A and 155A→G. Conclusion Some patients with unknown motor disturbance and mental retardation may suffer from BH4 metabolism related diseases. Theses patients are necessary to be screened for such kind of diseases in order to confirm the diagnosis.