Mitochondrial cytopathy is an older, umbrella term used to describe a heterogeneous group of disorders resulting from mitochondrial dysfunction, specifically involving defects in the mitochondrial respiratory chain, leading to impaired ATP production.

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### 🧬 What does the term mean?

* “Cytopathy” refers to cellular damage or disease; in this case, due to mitochondrial impairment. * It encompasses disorders caused by mutations in either mitochondrial DNA (mtDNA) or nuclear DNA that affect proteins essential for oxidative phosphorylation. * The clinical spectrum is broad, ranging from isolated organ involvement (e.g., optic atrophy or myopathy) to severe multisystem syndromes like MELAS, Leigh syndrome, or MERRF.

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### 🔍 Why is the term considered outdated or imprecise?

* It does not specify the genetic cause or the exact molecular defect. * It fails to indicate which respiratory chain complex is affected. * It blurs the line between primary mitochondrial disorders (genetically defined) and secondary mitochondrial dysfunction (e.g., due to toxins, aging, or acquired disease). * Modern classifications prefer terms like “primary mitochondrial disease (PMD)”, which reflect the genotype–phenotype relationship and guide diagnostic and therapeutic strategies more precisely.

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### ✅ Summary

* “Mitochondrial cytopathy” = a broad, historical term. * Now largely replaced by more specific nomenclature. * Still used in some clinical contexts when the diagnosis is suspected but not genetically confirmed.