BRCA1 is a high-risk susceptibility gene for breast and ovarian cancer. Pathogenic protein-truncating variants are scattered across the open reading frame, but all known missense substitutions that are pathogenic because of missense dysfunction are located in either the amino-terminal RING domain or the carboxy-terminal BRCT domain. Heterodimerization of the BRCA1 and BARD1 RING domains is a molecularly defined obligate activity. Hence, we tested every BRCA1 RING domain missense substitution that can be created by a single nucleotide change for heterodimerization with BARD1 in a mammalian two-hybrid assay. Downstream of the laboratory assay, we addressed three additional challenges: assay calibration, validation thereof, and integration of the calibrated results with other available data, such as computational evidence and patient/population observational data to achieve clinically applicable classification. Overall, we found that 15%–20% of BRCA1 RING domain missense substitutions are pathogenic. Using a Bayesian point system for data integration and variant classification, we achieved clinical classification of 89% of observed missense substitutions. Moreover, among missense substitutions not present in the human observational data used here, we find an additional 45 with concordant computational and functional assay evidence in favor of pathogenicity plus 223 with concordant evidence in favor of benignity; these are particularly likely to be classified as likely pathogenic and likely benign, respectively, once human observational data become available.

BRCA1是乳腺癌和卵巢癌的高危易感基因。致病性蛋白质截短变体分散在开放阅读框内，但所有已知的因错义功能障碍而致病的错义取代均位于氨基末端 RING 结构域或羧基末端 BRCT 结构域。 BRCA1 和 BARD1 RING 结构域的异二聚化是分子定义的专性活性。因此，我们在哺乳动物双杂交测定中测试了每个 BRCA1 RING 结构域错义取代，这些错义取代可以通过单核苷酸变化与 BARD1 异二聚化而产生。在实验室测定的下游，我们解决了三个额外的挑战：测定校准、其验证以及校准结果与其他可用数据（例如计算证据和患者/人群观察数据）的整合，以实现临床适用的分类。总体而言，我们发现 15%–20% 的BRCA1 RING 结构域错义替换具有致病性。使用贝叶斯点系统进行数据集成和变异分类，我们实现了 89% 观察到的错义替换的临床分类。此外，在此处使用的人类观察数据中不存在的错义替换中，我们发现另外 45 个具有一致的计算和功能分析证据支持致病性，加上 223 个具有一致的证据支持良性；一旦获得人类观察数据，这些病毒特别有可能分别被归类为可能致病的和可能良性的。