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NRTI Mitochondrial Toxicity — SCE Infectious Diseases MCQ

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HardHIV MedicineNRTI Mitochondrial ToxicitySCE Infectious Diseases

A person previously exposed to long-term zidovudine has slowly progressive myopathy, ragged-red fibres and cytochrome-c-oxidase-negative fibres. Which mechanism is most consistent?

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Correct answer: E — Legacy thymidine-analogue mitochondrial DNA depletion causing mitochondrial myopathy with review after review if needed

The best answer is “Legacy thymidine-analogue mitochondrial DNA depletion causing mitochondrial myopathy with review after review if needed”. Older thymidine analogues inhibit mitochondrial polymerase gamma; the biopsy pattern points to mitochondrial rather than inflammatory or nonspecific wasting disease. “Autoimmune polymyositis proved by any creatine-kinase elevation” does not match the decisive clinical feature or cited guidance. “Inclusion-body myositis caused directly by integrase inhibitors” does not match the decisive clinical feature or cited guidance. “Statin myopathy despite no statin exposure” does not match the decisive clinical feature or cited guidance. “HIV wasting without muscle pathology” does not match the decisive clinical feature or cited guidance.

Reference: BHIVA adult HIV treatment guideline: https://bhiva.org/clinical-guideline/hiv-1-treatment-guidelines/