What is Gamma-Sarcoglycanopathy?
Gamma-sarcoglycanopathy, also known as limb-girdle muscular dystrophy type 2C (LGMD2C), is caused by harmful genetic changes (mutations) in the SGCG gene and is a group of disorders that typically cause muscle weakness. Symptoms of the disease vary greatly from person to person, even among individuals in the same family. Some individuals with the disease can have a mild course, where they are nearly asymptomatic, while others may have severe symptoms that can be fatal.
Individuals with LGMD2C develop symptoms at different ages, though symptoms tend to present in early childhood. LGMD2C does not affect intelligence or mental function; the primary symptom is worsening (progressive) muscle weakness of the hip, shoulder, and abdomen. The rate at which the muscles weaken can vary, but the weakening often necessitates a wheelchair. Other features include enlarged calf muscles, shortening and hardening of muscles leading to rigid joints (contractures), prominence (winging) of the shoulder blades, and curvature of the spine (scoliosis). Respiratory complications or heart complications, such as arrhythmia or cardiomyopathy (seen in ~20% of individuals), are also associated with these conditions and may lead to death.
Individuals have also been described with only muscle pain during exercise, weak muscles close to the center of the body (proximal muscle weakness), or elevated creatine kinase levels with no known symptoms (hyperCKemia). These may not be distinct types of the condition, but instead, they represent the variable nature of the condition.
How common is Gamma-Sarcoglycanopathy?
The incidence of autosomal-recessive limb-girdle muscular dystrophy (LGMD) is 1 in 15,000 individuals. The percentage of LGMD cases attributed to LGMD2C is unknown. LGMD2C is more common in the North African and Roma populations.
How is Gamma-Sarcoglycanopathy treated?
There is no cure for gamma-sarcoglycanopathy and there are few effective treatments. Physical therapy helps retain muscle strength and mobility for as long as possible. Mobility aids, such as walkers, canes, braces, and wheelchairs, may become necessary. As muscles deteriorate, a machine that assists with breathing (a ventilator) may be needed. Cardiac surveillance is recommended, and individuals that develop heart problems should consult a heart specialist (cardiologist) for symptomatic treatments. Some individuals may need surgery if they develop scoliosis or contractures.
What is the prognosis for an individual with Gamma-Sarcoglycanopathy?
The outlook for an individual with LGMD2C varies. LGMD2C is considered one of the more severe forms of autosomal-recessive LGMD. Generally, the earlier symptoms begin, the faster they progress. However, because symptoms and onset can be variable, prognosis can be variable. In individuals with more severe symptoms, use of a wheelchair may become necessary in their early teens and death may occur in early adulthood. Causes of early death include respiratory and cardiac complications.