Limb-girdle muscular dystrophy

Synonyms

LGMD

Overview

Limb-girdle muscular dystrophy (LGMD) is an autosomal class of muscular dystrophy that is similar but distinct from Duchenne muscular dystrophy and Becker's muscular dystrophy. Limb-girdle muscular dystrophy encompasses a large number of rare disorders.

Symptoms

A person with LGMD generally has difficulty walking, going both up and down stairs and raising from a chair or a squatting position. Difficulty bending over and falling on a regular basis are also common. Difficulty lifting certain objects is also a common presentation of LGMD as well as difficulty holding your arms out or above your head. Eventually the ability to walk/run deteriorates. It is advised that someone with the disorder not put themselves in situations of potential peril. For example, walking on floors that have even the slightest incline can cause the individual to lose balance and fall. It is not recommended for someone with the disease to walk on terrain which is not stable such as ice or other slippery surfaces to avoid a severe injury. This is mainly due to the fact that LGMD weakens the leg muscles so an individual with LGMD would be more inclined to fall than someone who does not suffer from the disorder. At times, heart palpitation can occur.

Causes

LGMD is typically an inherited disorder, though it may be inherited as a dominant or recessive genetic defect. The result of the defect is that the muscles cannot properly form certain proteins needed for normal muscle function. Several different proteins can be affected, and the specific protein that is absent or defective identifies the specific type of muscular dystrophy. Among the proteins affected in LGMD are α, β, γ and δ sarcoglycans.

Prevention

Because it is a hereditary disorder, there is nothing an individual can do to prevent getting the disease. Because the weakness can affect the heart muscle, it is recommended that a doctor be aware of any heart-related symptoms so a cardiac pacemaker can be implanted to reduce the risk of sudden death due to an abnormal heart rhythm caused from the disease.

Diagnosis

Muscle biopsy:

Will show the presence of muscular dystrophy,

Genetic testing:

Used to determine which type of muscular dystrophy a patient has.

Prognosis

The distal muscles are affected late in LGMD, if at all. The disease typically causes loss of mobility or dependence on a scooter/wheelchair within 20 to 30 years of symptom onset. The various forms of LGMD are highly variable, and can be variable even among persons with the same form of LGMD. In its most severe form, LGMD2C, the symptoms are usually similar to Duchenne Muscular Dystrophy, with individuals losing the ability to walk between ages 10 and 12. In its mildest form, affected individuals have near-normal muscle strength and function.

While LGMD isn't typically a fatal disease, it may eventually weaken the heart and respiratory muscles, leading to illness or death due to secondary disorders. In its most severe form, LGMD2C, lifespans are typically limited to the 20s or early 30s. The mildest forms do not significantly affect lifespan.

Treatment

Although exercise and physical therapy are advised to maintain as much muscle strength and joint flexibility as possible, there are few studies corroborating the effectiveness of exercise. Physical therapy and exercise may prevent the rapid progression of the disease rather than halt or reverse it. Calipers may be used to maintain mobility and quality of life. Careful attention to lung and heart health is also required. IVIg may increase strength in some forms and prevent progression in others, possibly through the prevention of fibrosis and inflammation without the secondary weakening caused by corticosteroids.