Cytochrome C oxidase-negative muscle fibers

What it means

An abnormally reduced activity of the enzyme cytochrome C oxidase in muscle tissue.

This abnormality can be assayed by muscle biopsy. Cytochrome C oxidase is an enzyme of the respiratory electron transport chain of mitochondria that is located in the mitochondrial membrane.

Rare diseases that can present with this4

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Cytochrome c oxidase deficiency in skeletal muscle · Cytochrome C oxidase-negative muscle fibres · Decreased activity of cytochrome C oxidase in muscle tissue · Decreased skeletal muscle cytochrome c oxidase activity