The Arg482His mutation in the β-galactosidase gene is responsible for a high frequency of GM1 gangliosidosis carriers in a Cypriot village
The Arg482His mutation in the β-galactosidase gene is responsible for a high frequency of GM1 gangliosidosis carriers in a Cypriot village
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DOI：
10.1089/gte.2005.9.126
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发表时间：
2005-06-01
期刊：
影响因子：
--
通讯作者：
Drousiotou, A
中科院分区：
文献类型：
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作者：
Georgiou, T;Stylianidou, G;Drousiotou, A
GM1神经节苷脂贮积症是一种由β-半乳糖苷酶缺乏引起的溶酶体贮积症。它主要以进行性神经变性为特征，在其最严重的婴儿型中，患者会在4岁前死亡。GLB1基因产生两种可变剪接的mRNA，它们编码β-半乳糖苷酶和弹性蛋白结合蛋白（EBP）。在塞浦路斯一个小山村中两名婴儿型GM1神经节苷脂贮积症患者和11名携带者的诊断促使我们开展一项研究，以确定该村携带者的频率并识别相关突变。携带者检测最初基于白细胞中β-半乳糖苷酶活性的测量。在来自该村的85个随机样本中，有10个被归类为携带者。对一名塞浦路斯患者的GLB1基因测序确定了纯合状态下的错义突变c.1445G > A（p.Arg482His）。通过NspI限制酶分析发现，使用酶检测法确定的10名携带者中有7名携带相同突变。c.1445G > A检测为阴性的3个人酶检测结果处于临界值，可能被错误地归类为携带者。这个村庄中GM1神经节苷脂贮积症携带者的频率约为8%（1∶12）。蛋白质印迹分析显示，该酶蛋白64 kDa的成熟形式显著减少，67 kDa的EBP也有类似的减少。我们的结果表明，c.1445G > A突变似乎是这个塞浦路斯村庄中所有GM1神经节苷脂贮积症等位基因的致病原因，它影响蛋白质构象。
GM1 gangliosidosis is a lysosomal storage disorder caused by deficiency of beta-galactosidase. It is mainly characterized by progressive neurodegeneration, and in its most severe infantile form, it leads to death before the age of 4. The GLB1 gene gives rise to two alternatively spliced mRNAs that encode the beta-galactosidase and the elastin binding protein (EBP). The diagnosis of two patients with the infantile form of GM1 gangliosidosis and 11 carriers in a small mountainous village in Cyprus prompted us to carry out a study in order to establish the frequency of carriers in the village and identify the mutations involved. Carrier detection was initially based on the measurement of beta-galactosidase activity in leucocytes. Among 85 random samples from the village, 10 were classified as carriers. Sequencing of the GLB1 gene in a Cypriot patient identified the missense mutation c. 1445G > A ( p. Arg482His) in the homozygous state. Seven of the 10 carriers identified using the enzyme assay were found to carry the same mutation by NspI restriction enzyme analysis. The three individuals who were negative for the c. 1445G > A had borderline enzyme results and were probably wrongly classified as carriers. The frequency of GM1 gangliosidosis carriers in this village is approximately 8% ( 1: 12). Western blot analysis showed a marked decrease of the 64-kDa mature form of the enzyme protein and a similar reduction of the 67-kDa EBP. Our results indicate that the c. 1445G > A mutation, which appears to be responsible for all GM1 gangliosidosis alleles in this Cypriot village, affects protein conformation.