Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.
Università Cattolica del Sacro Cuore, Rome, Italy.
Mol Diagn Ther. 2019 Feb;23(1):121-126. doi: 10.1007/s40291-018-0376-2.
In recent years, the number of patients being offered BRCA1/2 testing has changed dramatically. Advances in high-throughput sequencing technology have led many diagnostic laboratories to test next-generation sequencing (NGS)-based platforms as the main technology for clinical testing. As a consequence, the proportion of novel BRCA1/2 variants detected has greatly increased. Here, we describe two novel BRCA1 large deletions detected in Italian patients affected by hereditary breast and ovarian cancer syndrome (HBOC).
We applied an NGS pipeline with a reliable copy number variation (CNV) prediction algorithm. Successively, samples were investigated using the Multiplex Amplicon Quantification (MAQ) assay and array comparative genomic hybridization (CGH). In a single case, long-range polymerase chain reaction (PCR) was employed for careful detection of the breakpoint region, while the RepeatMasker program was used to identify Alu sequences at the junction point.
A 137.8 kb deletion, involving the first six exons of BRCA1 and the full NBR2, BRCA1P1, NBR1, and TMEM106a genes, was detected in an Italian woman diagnosed with high-grade serous ovarian carcinoma. A second rearrangement, involving the deletion of BRCA1 11-14 exons, was detected in a breast cancer patient and was fully characterized and reported according to recommended Human Genome Variation Society (HGVS) nomenclature: NG_005905.2: g.125038_143266del; NM_007294.3: c.2817_4716del; NP_009225: p.Lys862Metfs?
Although it was not possible to perform a familial segregation analysis and more direct evidence of the relationship between genotype and phenotype is necessary, both of the novel reported rearrangements cause the loss of crucial functional domains of the BRCA1 protein and this event supports their pathogenicity.
近年来，提供 BRCA1/2 检测的患者数量发生了巨大变化。高通量测序技术的进步促使许多诊断实验室将基于下一代测序（NGS）的平台作为临床检测的主要技术。因此，检测到的新的 BRCA1/2 变体的比例大大增加。在这里，我们描述了在意大利遗传性乳腺癌和卵巢癌综合征（HBOC）患者中检测到的两种新型 BRCA1 大片段缺失。
我们应用了一种具有可靠拷贝数变异（CNV）预测算法的 NGS 管道。随后，使用多重扩增定量（MAQ）测定和阵列比较基因组杂交（CGH）对样品进行了研究。在一个单一的情况下，使用长距离聚合酶链反应（PCR）来仔细检测断点区域，而重复掩蔽程序用于识别在连接点的 Alu 序列。
在一名被诊断为高级别浆液性卵巢癌的意大利女性中，检测到涉及 BRCA1 的前六个外显子和完整的 NBR2、BRCA1P1、NBR1 和 TMEM106a 基因的 137.8kb 缺失。在一名乳腺癌患者中检测到第二个涉及 BRCA1 11-14 个外显子缺失的重排，并根据推荐的人类基因组变异协会（HGVS）命名法进行了全面表征和报告：NG_005905.2：g.125038_143266del; NM_007294.3：c.2817_4716del; NP_009225：p.Lys862Metfs？
尽管无法进行家族分离分析，并且需要更多直接的基因型与表型关系的证据，但这两种新型报道的重排均导致 BRCA1 蛋白的关键功能域缺失，这一事件支持其致病性。
