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Related Experiment Video

Updated: May 26, 2026

Tissue Triage and Freezing for Models of Skeletal Muscle Disease

Tissue Triage and Freezing for Models of Skeletal Muscle Disease

Published on: July 15, 2014

Congenital fiber-type disproportion.

Nigel F Clarke¹

¹Institute of Neuroscience and Muscle Research, Children's Hospital at Westmead, Discipline of Paediatrics & Child Health, University of Sydney, Westmead, New South Wales, Australia. nigel.clarke@health.nsw.gov.au

Seminars in Pediatric Neurology

|December 17, 2011

Summary

Congenital fiber-type disproportion, a congenital myopathy syndrome, is defined by smaller type 1 muscle fibers. Genetic causes are increasingly identified, necessitating respiratory function monitoring.

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Last Updated: May 26, 2026

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Fiber Type Identification of Human Skeletal Muscle

Fiber Type Identification of Human Skeletal Muscle

Published on: September 22, 2023

Area of Science:

Neurology
Muscle Biology
Genetics

Background:

Congenital fiber-type disproportion (CFD) is a congenital myopathy characterized by specific muscle fiber size abnormalities.
It is increasingly recognized as a syndrome with diverse underlying causes rather than a single entity.
The defining histological feature is type 1 fibers being significantly smaller than type 2 fibers.

Purpose of the Study:

To review the current understanding of congenital fiber-type disproportion.
To highlight diagnostic considerations and the spectrum of genetic causes.
To emphasize the importance of respiratory function monitoring in affected individuals.

Main Methods:

Review of existing literature on congenital fiber-type disproportion.
Analysis of histological findings and genetic associations.
Discussion of clinical management strategies, particularly respiratory surveillance.

Main Results:

The core histological finding is a size discrepancy between type 1 and type 2 muscle fibers (≥35-40% smaller type 1).
This finding can be present in other neuromuscular disorders, requiring careful differential diagnosis.
Numerous genetic causes underlying CFD have been identified, contributing to its syndromic classification.

Conclusions:

Congenital fiber-type disproportion is best conceptualized as a syndrome with a characteristic histological pattern.
Accurate diagnosis requires differentiating it from other myopathies and neuromuscular conditions.
Ongoing surveillance of respiratory function is crucial for patient management until specific genetic causes and individualized advice are established.