What Are the Basics of Limb Girdle Muscular Dystrophy?

Q:
What are the basics of limb girdle muscular dystrophy?

A:
Limb-girdle muscular dystrophy (LGMD) or Erb’s muscular dystrophy is a group of rare, progressive and genetic disorders. The subtypes of LGMD are categorized by disease gene and inheritance. LGMD usually occurs in the proximal muscles around the hips and shoulders.

Causes

LGMD is a genetic disorder that is inherited as either an autosomal recessive or dominant trait. The autosomal recessive forms account for 90 percent of cases, according to National Organization for Rare Disorders (NORD). Genetic disorders are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother. Researchers have identified many different subtypes of LGMD, each one resulting from a mutation of a different disease gene (genetic heterogeneity).

Signs and Symptoms

The major symptoms of LGMD are progressive wasting (atrophy) and weakness of the proximal muscles of the hip and shoulder areas. However, the age at onset, severity, and progression of symptoms associated with LGMD may vary greatly from case to case, even among members of the same family.

Additional abnormalities that may develop in individuals with LGMD include:

  • abnormal side-to-side curvature of the spine (scoliosis);
  • abnormal front-to-back curvature of the spine (lordosis);
  • thickening and shortening of tissue that cause deformity and restricts movement of affected areas,
  • especially the joints (contractures);
  • overgrowth (hypertrophy) of certain muscles
  • weakness of the heart muscle (cardiomyopathy)
  • abnormal transmission of signals that regulate the heartbeat (conduction abnormalities or arrhythmias)

Diagnosis

A diagnosis of LGMD is made based upon:

  • a thorough clinical evaluation,
  • a detailed patient history,
  • identification of characteristic symptoms (e.g., specific distribution of muscle weakness and atrophy),
  • a variety of specialized tests

The tests may include:

  • surgical removal and microscopic examination (biopsy) of affected muscle tissue that may reveal characteristic changes to muscle fibers;
  • a test that assesses the health of muscles and the nerves that control muscles (electromyography);
    specialized blood tests;
  • tests that evaluate the presence and number of certain muscle proteins (immunohistochemistry);
    molecular genetic testing.
Treatment

Standard Therapies
There is no cure for any form of LGMD. The specific symptoms present in each individual will determine which treatments they should opt for. Specific treatment options may include:

  • physical and occupational therapy to improve muscle strength and prevent contractures;
  • the use of various devices (e.g., canes, braces, walkers, wheelchairs) to assist with walking (ambulation) and mobility;
  • surgery to correct skeletal abnormalities such as scoliosis;
  • regular monitoring of the heart and the respiratory system for the development of such complications potentially associated with some forms of LGMD.

 

Keywords: limb girdle muscular dystrophy; LGMD

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.