PDF(Pubmed)
Abstract：
For patients with hereditary breast and ovarian cancer, the probability of carrying two pathogenic variants (PVs) in dominant cancer-predisposing genes is rare. Using targeted next-generation sequencing (NGS), we investigated a 49-year-old Caucasian woman who developed a highly aggressive breast tumor. Our analyses identified an intragenic germline heterozygous duplication in BRCA1 with an additional likely PV in the TP53 gene. The BRCA1 variant was confirmed by multiplex ligation probe amplification (MLPA), and genomic breakpoints were characterized at the nucleotide level (c.135-2578_442-1104dup). mRNA extracted from lymphocytes was amplified by RT-PCR and then Sanger sequenced, revealing a tandem duplication r.135_441dup; p.(Gln148Ilefs*20). This duplication results in the synthesis of a truncated and, most likely, nonfunctional protein. Following functional studies, the TP53 exon 5 c.472C > T; p.(Arg158Cys) missense variant was classified as likely pathogenic by the Li-Fraumeni Syndrome (LFS) working group. This type of unexpected association will be increasingly identified in the future, with the switch from targeted BRCA sequencing to hereditary breast and ovarian cancer (HBOC) panel sequencing, raising the question of how these patients should be managed. It is therefore important to record and investigate these rare double-heterozygous genotypes.
摘要：
对于遗传性乳腺癌和卵巢癌患者，在显性癌症易感基因中携带两种致病变异体(PV)的可能性很少.使用靶向下一代测序（NGS），我们调查了一名49岁的白人女性,她发展了一种高度侵袭性的乳腺肿瘤.我们的分析确定了BRCA1中的基因内种系杂合子复制，TP53基因中可能有额外的PV。通过多重连接探针扩增(MLPA)确认BRCA1变体,和基因组断点在核苷酸水平表征（c.135-2578_442-1104dup）。通过RT-PCR扩增从淋巴细胞中提取的mRNA，然后进行Sanger测序，揭示串联重复r.135_441dup；p.(Gln148Ilefs*20)。这种重复导致合成的截断和，最有可能的是,无功能蛋白质。在功能研究之后，TP53外显子5c.472C>T;p。（Arg158Cys）错义变异被Li-Fraumeni综合征（LFS）工作组归类为可能致病。这种类型的意外关联将在未来越来越多地被识别,随着从靶向BRCA测序到遗传性乳腺癌和卵巢癌（HBOC）组测序的转变，提出了如何管理这些患者的问题。因此，重要的是记录和研究这些罕见的双杂合基因型。
