What are the key factors guiding the use of cascade testing in HBOC and Lynch families?

• A. A pathogenic variant found in an affected individual informs testing of first-degree relatives to determine who at risk for cancer and may benefit from surveillance
• B. Cascade testing is optional and not recommended
• C. Cascade testing only applies to siblings
• D. Cascade testing should be avoided due to privacy concerns

Answer: (A)

When a pathogenic variant is identified in an affected family member, the essential step is cascade testing to extend testing to close relatives who are at meaningful risk. In HBOC and Lynch families, first-degree relatives (parents, siblings, and children) have a substantial chance of carrying the same variant because these conditions are typically inherited in an autosomal dominant manner. Testing these relatives helps determine who actually carries the variant and thus who is at elevated cancer risk, enabling targeted, timely surveillance and preventive actions. This approach translates a genetic finding into concrete care: earlier or more frequent breast/ovarian cancer screening for HBOC and earlier colonoscopy surveillance for Lynch, with consideration of risk-reducing options where appropriate. cascade testing is generally recommended and conducted with genetic counseling and informed consent, and while privacy concerns are important, they should be balanced against the clear benefits of identifying carriers. It is not limited to siblings and is not merely optional; it expands to all at-risk relatives who may benefit from knowing their status.