Cascade screening – CF sibling — RACP Paediatrics MCQ

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ModerateGeneticsCascade screening – CF siblingRACP Paediatrics

A 2-year-old sibling of a child with CF needs to be tested to determine if they are a carrier. The affected sibling's CFTR mutations are known. What type of genetic testing is this?

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Correct answer: D — Cascade family screening

Testing a sibling for carrier status of a known familial mutation is cascade (family) screening. For CF, knowing both familial mutations allows targeted testing of the sibling. If a carrier (one mutation), this has reproductive implications in adulthood. If two mutations are found, the sibling has CF (even if asymptomatic – relevant for late-presenting phenotypes).

Reference: RACP Paediatric Curriculum – Genetics; Australian Guidelines on Genetic Testing