BRCA1/2 genes with high-penetrance are tumor suppressor and tumor susceptibility genes that play important roles in the homologous recombination mechanism in DNA repair and increase breast cancer risk. Variants in BRCA1 or BRCA2 are the main causes of familial and early-onset breast cancer. This study investigated pathogenic variant belonging to the BRCA2 gene splice region in monozygotic triplets. A 44-year-old woman was diagnosed with breast cancer when she was 32 years old. Her monozygotic sister had a history of breast cancer. No malignancy was detected in the third one of the monozygotic triplets. Sanger sequencing was used to evaluate the BRCA1/2 gene status of the patient and family members. It was figured out that they had the same genetic variant, a heterozygous germ-line splice region variant (c.7008-1G > C) in the BRCA2 gene. This novel splice region variant may be a new pathogenic variant of the BRCA2 gene. Its association with breast cancers needs to be further verified in more patient cases.

具有高穿透性的BRCA1 / 2基因是肿瘤抑制基因和易感基因，在DNA修复的同源重组机制中起着重要作用，并增加了患乳腺癌的风险。BRCA1或BRCA2的变异是家族性和早发型乳腺癌的主要原因。这项研究调查了在单合三胞胎中属于BRCA2基因剪接区的致病变异。一名44岁的女性在32岁时被诊断出患有乳腺癌。她的单卵姐妹有乳腺癌病史。在第三个单卵三胞胎中未检测到恶性肿瘤。Sanger测序用于评估BRCA1 / 2患者及其家庭成员的基因状态。已发现它们具有相同的遗传变异，即BRCA2基因中的杂合种系剪接区变异（c.7008-1G> C）。这种新的剪接区变异可能是BRCA2基因的新致病变异。在更多的患者病例中，其与乳腺癌的关联需要进一步验证。