Genetic Testing and Counselling Quiz

See Section. Option E is correct: this is diagnostic genetic testing because the clinician is investigating symptoms the patient already has. The phenotype, meaning the observable clinical features, is unexplained muscle weakness. Testing seeks a genetic finding that could explain those features rather than estimating the future risk of an unaffected person. The clinical question determines which genes or types of chromosome change should be investigated. The same laboratory technology can be used for different purposes, so a blood sample or sequencing method does not by itself tell you whether testing is diagnostic. A negative result also needs to be interpreted within what that particular test could detect.

Carrier testing (D) usually asks whether an unaffected person carries a disease-associated variant that could affect reproductive risk, rather than explaining current weakness. B is population screening: an offer to a defined group to identify people who may need further assessment. Predictive testing (A) concerns a healthy relative's future risk, often by testing for a known familial variant. Pharmacogenomic testing (C) examines genetic influences on drug response, toxicity or dose, which is a prescribing question rather than a diagnosis of this patient's symptoms.