Type 1 fibers relatively smaller than type 2 fibers

What it means

The presence of abnormal muscle fiber size such that type 1 fibers are smaller than type 2 fibers.

This feature can only be observed on muscle biopsy.

Rare diseases that can present with this1

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: Type 1 fibres relatively smaller than type 2 fibres