Merck Manual

Please confirm that you are a health care professional

honeypot link

Introduction to Inherited Muscular Disorders


Michael Rubin

, MDCM, New York Presbyterian Hospital-Cornell Medical Center

Reviewed/Revised Jan 2024

Muscular dystrophies are distinguished by the selective distribution of weakness and the specific nature of the genetic abnormality involved.

Congenital muscular dystrophy

Congenital muscular dystrophy describes a rare group of diseases with symptoms evident at birth or shortly thereafter. The diseases are genetically recessive and manifest with diminished muscle tone, sometimes called "floppy baby." Diagnosis is based on clinical presentation, muscle biopsy, and blood tests to evaluate muscle proteins and genetic abnormalities. No cure exists; treatment is focused on preserving and optimizing function.

Congenital muscular dystrophy is not a single disorder but instead refers to muscular dystrophy evident at birth or in infancy, occurring from any of several rare forms of muscular dystrophy. All such dystrophies are genetically recessive and result from mutations in a variety of different genes, including those that encode for structural proteins of the basal membrane or the extracellular matrix of skeletal muscle fibers.

The diagnosis of congenital muscular dystrophy is suspected in any floppy neonate but must be distinguished from a congenital myopathy Congenital Myopathies Congenital myopathy is a term sometimes applied to hundreds of distinct neuromuscular disorders that may be present at birth, but it is usually reserved for a group of rare, inherited... read more by muscle biopsy. Blood tests to evaluate muscle proteins, ultrasonography and magnetic resonance imaging of muscle, and genetic testing when available, are typically done to arrive at an accurate diagnosis.

No specific treatment exists for congenital muscular dystrophies. Orthopedic, cardiac, respiratory, nutritional, and social issues may be addressed by appropriate experts as the needs arise, and supportive care, including physical therapy helps preserve function.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz!