TSC2基因c.2355+1G>C变异致轻型结节性硬化症一例

A case of tuberous sclerosis complex due to a novel splicing variant of TSC2 gene

目的探讨1例结节性硬化症(tuberous sclerosis complex,TSC)患者可能的遗传学病因。方法应用高通量测序技术、多重连接探针扩增技术和Sanger测序技术对1例疑似结节性硬化症患者行基因变异分析,并在家系其他成员及100名正常对照中进行验证;通过反转录-PCR及Sanger测序技术确定该变异可能导致的mRNA转录变化。结果测序结果显示该家系中先证者发生了TSC2基因的c.2355+1G>C杂合变异,cDNA的序列分析表明该变异导致TSC2基因在第21外显子3′端插入62个碱基序列,这种剪切位点变化导致蛋白翻译提前终止,预测产生截短蛋白。结论TSC2基因c.2355+1G>C变异可能是该患者的致病原因。本研究结果不仅进一步丰富了TSC2基因的变异谱,同时为产前诊断和胚胎植入前遗传学检测的开展提供了理论基础。

Objective To explore the genetic basis for a patient with tuberous sclerosis complex.Methods Genomic DNA was extracted from peripheral blood samples from members of his family and 100 unrelated healthy controls.The proband was subjected to next-generation sequencing,and candidate variant was confirmed by multiple ligation-dependent probe amplification(MLPA)and Sanger sequencing.Reverse transcription-PCR(RT-PCR)was carried out to determine the relative mRNA expression in the proband.Results The patient was found to harbor a c.2355+1G>C splicing variant of the TSC2 gene.Sequencing of cDNA confirmed that 62 bases have been inserted into the 3′end of exon 21,which has caused a frameshift producing a truncated protein.Conclusion The novel splicing variant c.2355+1G>C of the TSC2 gene probably underlay the TSC in the proband.Above finding has expanded the variant spectrum of TSC2 and provided a basis for preimplantation genetic testing and/or prenatal diagnosis.