结节性硬化症TSC1基因编码外显子全长的突变检测与分析

Mutation analysis of TSC1 gene in Chinese patients with tuberous sclerosis complex

目的研究结节性硬化症(TSC)TSC1基因所有编码外显子的基因突变特征和多态现象。方法采用聚合酶链反应单链构象多态(PCR SSCP)技术结合DNA测序对来源于21个家系的23例TSC患者、22名父母及60名健康对照进行TSC1基因编码外显子全长的基因突变和多态的检测。结果共检测出10种异常的SSCP带型,经DNA测序后证实为4种突变和6种多态,突变包括2种移码突变(352insA和2332insT)、1种剪接突变(729+1G→T)、1种无义突变Tyr761Ter(2504C→A),其中2332insT, 729+1G→T及Tyr761Ter为新型突变。以上突变均见于散发型患者,突变频率为4 /15。6种多态包括4种单核苷酸多态(347A→C, 1186T→C, 1556A→G, 1947T→C), 1种内含子区多态(2218+71delAG)及1种3′UTR区多态(3716+36T→C),其中3种为新多态。结论本组结果对研究我国TSC1基因突变特征提供了重要资料,未发现TSC1基因突变热区,且TSC1基因突变多见于散发型患者,提示中西方TSC1基因突变可能存在差异。

Objective To identify TSC1 gene mutations by single stranded conformation polymorphism (SSCP) analysis and direct sequencing.Methods Tolally 23 patients with confirmed clinical manifestations of TSC and 22 parents of the patients coming from 21 TSC families were included in the study. In total, we studied 6 familial cases and 15 sporadic cases. A total of 10 variants were detected by SSCP.Results After being confirmed by DNA direct sequencing, mutations were identified in 4/15 sporadic cases, in which there were 2 small insertions (352insA and 2332insT), 1 nonsense mutation (Tyr761Ter) and 1 splice mutation (729+1G→T). All of them led to a premature stop codon and resulted in a truncated protein. However, we did not find mutations in cases from 6 small families,but found 6 polymorphisms which included 3 novel polymorphisms. Of the 6 TSC1 polymorphisms, four were single nucleotide polymorphism (SNP), 347 A→C ,1186T→C, 1556A→G, 1556A→G, resulting in silent changes, in which one was intronic (2218+71delAG), and one was in the 3′UTR(3716+36T→C). Conclusion Our study shows no mutational hotspot in Chinese patients, but improves our knowledge in mutation characteristics of TSC1 gene in the Chinese.