The Variant of Uncertain Significance in a Family With No Living Affected Relative
A 34-year-old woman (proband) is referred after her mother died of ovarian cancer at 52 and her maternal aunt died of breast cancer at 47. The proband is unaffected. Her mother's archival tumor tissue was tested and reported a BRCA2 variant, c.7397T>C, classified by the laboratory as a Variant of Uncertain Significance (VUS). No other relatives have been tested. The proband's only living maternal relative is a 60-year-old unaffected uncle. The proband asks whether she should have predictive testing and whether she should pursue risk-reducing salpingo-oophorectomy (RRSO) now, since she wants to complete childbearing within 2 years. Her insurance does not cover multi-gene panel testing, only single-site testing.
1. How should the counselor frame the meaning of the VUS for the proband, and what testing strategy is appropriate given the single-site coverage constraint?
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A VUS is not actionable as a pathogenic result: it must not be used to make surgical or surveillance decisions. The key reasoning step is that a VUS can be reclassified, and the proband's mother's tumor result does not by itself establish that the variant caused the cancers. Because the proband is unaffected, single-site testing for the VUS is technically feasible but only useful if the family can later clarify the variant's significance. The counselor should explain that a positive single-site result would still be a VUS, not a diagnosis, and that a negative result would be uninformative about her cancer risk. Given the family history (two first/second-degree relatives with HBOC-spectrum cancers), the proband still meets criteria for high-risk surveillance based on family history alone, independent of the VUS. The counselor should advocate for panel testing or a laboratory's variant reclassification/functional assay program, and document that the single-site approach is a coverage-driven limitation rather than the preferred strategy.
2. The uncle is the only living relative who could provide segregation information. What are the ethical and practical considerations in approaching him, and how would his result change management?
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The counselor should first clarify whether the proband is willing to disclose her mother's result to the uncle and whether the mother's estate or the proband holds authority to share it; genetic information about a deceased relative is generally shared at the discretion of the living family, but the counselor should avoid disclosing without the proband's consent. Practically, the uncle's value is limited: he is unaffected and male, and a BRCA2 VUS in an unaffected man provides little segregation evidence because absence of cancer in a 60-year-old man is not strongly informative for a breast/ovarian variant. If he carries the variant, it confirms it is familial but does not reclassify it; if he does not, the variant may be a private change in the mother, weakening its relevance. In neither case does the VUS become actionable. Management should therefore be driven by the family history-consideration of earlier/ intensified breast surveillance and discussion of RRSO timing based on family pattern-not by the uncle's result. The counselor should set expectations that segregation in a single unaffected relative rarely resolves a VUS.