Gorlin-Goltz综合征(GS)是一种遗传性疾病,其特征是对基底细胞癌(BCC)和各种发育缺陷的易感性,已在hedgehog(Hh)信号通路中鉴定出许多引起疾病的PTCH1突变。
在这项研究中,使用全外显子组测序在3个具有致命性GS的姐妹中筛选体细胞和种系有害突变.我们发现的突变通过基因组DNA的亚克隆和Sanger测序得到证实。进行RNA-seq以在配对的BCC样品中描述基因表达,并且通过定量PCR验证所选基因的表达水平。
分析了三代GS家族先证者的临床和组织病理学特征。我们鉴定了插入突变PTCH1c.1341dupA(p。L448Tfs*49),与BCC表型分离,并导致四分之一来自中国GS家庭的患者死亡。与邻近的非癌组织(ANCT)相比,在3例患者的6对BCC中的4对中发现了4个二次命中突变.值得注意的是,所有六个BCC样品中的体细胞基因组改变主要集中在非时钟样签名7(紫外线诱变)和11(与某些烷化剂有关)中。RNA-seq和定量RT-PCR均证实,与ANCT相比,六对BCC样品中PTCH1及其效应子GLI1的mRNA水平显着上调。
BCC明显的非时钟样特征表明GS不是危及生命的疾病。GS患者过早死亡的主要原因是PTCH1突变,暴露于强烈的紫外线辐射和恶劣的经济条件。
BACKGROUND: Gorlin-Goltz syndrome (GS) is an inherited disease characterized by predisposition to basal cell carcinomas (BCCs) and various developmental defects, whose numerous disease-causing PTCH1 mutations have been identified in the hedgehog (Hh) signaling pathway.
METHODS: In this study, whole exome sequencing was used to screen for both somatic and germline deleterious mutations in three sisters with a lethal GS. The mutations we found were confirmed by subcloning and Sanger sequencing of the genomic DNA. RNA-seq was performed to profile gene expression in paired BCCs samples and the expression levels for selected genes were validated by quantitative PCR.
RESULTS: The clinical and histopathologic features were analyzed for the proband in the three-generation GS family. We identified the insertion mutation PTCH1 c.1341dupA (p. L448Tfs*49), which segregated with BCC phenotype and contributed to the death of two in four patients from a Chinese family with GS. Compared with adjacent non-cancerous tissues (ANCT), four second-hit mutations were found in four of the six pairs of BCC from three patients. Of note, somatic genomic alterations in all six BCC samples were mainly clustered into non-clock-like Signature 7 (ultraviolet mutagenesis) and 11 (related to certain alkylating agents). Both RNA-seq and quantitative RT-PCR confirmed that the mRNA levels of PTCH1 and its effector GLI1 were markedly upregulated in six pairs of BCC samples versus ANCT.
CONCLUSIONS: The distinct non-clock-like signatures of BCCs indicated that GS was not a life-threatening illness. The main reasons for untimely death of GS patients were PTCH1 mutation, exposure to intense ultraviolet radiationand the poor economic conditions.