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Congenital Myopathies

By

Michael Rubin

, MDCM, New York Presbyterian Hospital-Cornell Medical Center

Last full review/revision Jul 2020
CLICK HERE FOR THE PROFESSONAL VERSION

Congenital myopathies are rare, inherited disorders of the muscles that cause reduced muscle tone and weakness. These disorders are present at birth or show up during infancy.

There are several types of congenital myopathies. The three most common types of congenital myopathy are

  • Central core and multiminicore myopathies (core myopathies)

  • Centronuclear myopathy

  • Nemaline myopathy

Symptoms and lifespan vary with the type and severity of the myopathy.

Central core myopathy and multiminicore myopathy (core myopathies)

Central core myopathy and multiminicore myopathy are the most common form of congenital myopathy.

Most newborns have severely reduced muscle tone (hypotonia, or "floppiness") and mild muscle weakness Weakness Weakness refers to loss of muscle strength. That is, people cannot move a muscle normally despite trying as hard as they can. However, the term is often misused. Many people with normal muscle... read more , but sometimes symptoms of core myopathy do not manifest until adulthood. Many people also have facial weakness. The weakness does not become worse, and life expectancy is normal, but some people are severely affected and require a wheelchair. People who have central core myopathy are at increased risk of a life-threatening disorder called malignant hyperthermia Malignant Hyperthermia Malignant hyperthermia is a rare, life-threatening rise in body temperature that occurs in susceptible people who are given certain muscle-relaxing drugs plus an anesthetic gas for surgery.... read more .

Centronuclear myopathy

Centronuclear myopathies are inherited in various ways. The forms that are inherited via a gene carried on the X chromosome (see X-Linked Inheritance X-Linked Inheritance Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more ) are the most common and most severe, and most affected children do not survive beyond the first year of life. Symptoms of the autosomal dominant Dominant disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more forms typically appear in adolescence or adulthood. People who have one of these forms have muscle pain caused by exercise, facial weakness, droopy eyelids, and weakness of the eye muscles.

Nemaline myopathy

Nemaline myopathy may be severe, moderate, or mild. People who have a severe form may have weakness of the muscles used for breathing and respiratory failure Respiratory Failure Respiratory failure is a condition in which the level of oxygen in the blood becomes dangerously low or the level of carbon dioxide in the blood becomes dangerously high. Conditions that block... read more . People who have a moderate form may have weakness in muscles of the face, neck, trunk, and feet that becomes worse over time, but their life expectancy may be nearly normal. People who have a mild form have weakness that does not worsen, and their life expectancy is normal.

Diagnosis of Congenital Myopathies

  • Symptoms of weakness

  • Muscle biopsy

The diagnosis of congenital myopathy is based on characteristic symptoms of weakness that are caused by each specific type.

Doctors confirm the diagnosis by taking a sample of the weak muscle tissue for biopsy (removal of a piece of tissue for examination under a microscope).

Treatment of Congenital Myopathies

More Information

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

NOTE: This is the Consumer Version. DOCTORS: CLICK HERE FOR THE PROFESSONAL VERSION
CLICK HERE FOR THE PROFESSONAL VERSION
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