粘多糖贮积症Ⅱ型患者艾杜糖-2-硫酸酯酶基因常见突变的检测

目的 探讨并建立粘多糖贮积症Ⅱ型（mucopolysaccharidosis Ⅱ,MPSⅡ)患者艾杜糖－2－硫酸酯酶（iduronate-2-sulphatase,IDS)基因常见突变的检测方法。方法 应用聚合酶链反应－单链构象多态性（polymerase chain reaction-single strand conformation polymorphism,PCR-SSCP）对IDS基因突变热点外显子3、8和9进行点突变检测；应用DNA测序对PCR－SSCP检出的突变进行序列分析；应用聚合酶链反应－限制性片段长度多态性（polymerase chain reaction-restriction fragment length polymorphism,PCR-RFLP)对DNA测序的结果进行检测。结果 以PCR－SSCP发现该患者的IDS基因外显子9有明显异常泳动的条带；DNA测序发现患儿的外显子9发生点突变（C1672T），从而导致患者艾杜糖－2－硫酸酯酶蛋白发生氨基酸替换（R468W）；PCR－RFLP电泳检测结果显示粘多糖贮积症Ⅱ型患者仅出现554bp 1条带，而患儿父母出现257bp和297bp 2条带，进一步验证了序列分析的结果。结论 PCR－SSCP分析、DNA序列分析和PCR－RFLP分析是诊断MPSⅡ的有效方法，三者联合使用可以相互验证、互为补充，提高基因诊断的准确率和成功率。

The detection of the frequent mutations of iduronate-2-sulphatase gene in mucopolysaccharidosis type Ⅱ patients in Chinese

OBJECTIVE: To investigate and establish the gene diagnosis methods for the frequent mutations of iduronate-2-sulphatase(IDS) gene in mucopolysaccharidosis type II patients. METHODS: polymerase chain- reaction-single strand conformation polymorphism PCR-SSCP) analysis was applied to detect the mutations of exons 3, 8 and 9 which were hot spots in the iduronate-2-sulfatase gene; DNA sequencing was applied to analyze the mutations which had been detected by PCR-SSCP; PCR-restriction fragment length polymorphism (PCR-RFLP) was applied to detect the results of DNA sequencing. RESULTS: Obvious and abnormal bands in exon 9 of the IDS gene were found by applying PCR-SSCP; the mutation(C1672T) of exon 9 was found in the patient through DNA sequencing, which led to amino acid replacement(R468W); the PCR-restriction enzyme digestion showed that only one band(554 bp) appeared in the patient, but there were two bands (257 bp and 297 bp) in his parents, and it verified the results of sequencing analysis. CONCLUSION: PCR-SSCP analysis, DNA sequencing analysis and PCR-restriction enzyme digestion are effective methods for MPS II diagnosis. Combined applications of these methods can verify and complement each other and improve the accuracy of diagnosis.