What is Calpainopathy?
Calpainopathy (also known as limb-girdle muscular dystrophy type 2A or LGMD2A) represents a spectrum of disorders that cause muscle weakness as a result of a deficiency of the protein, calpain-3. Symptoms of the disease vary greatly from person to person, even among people in the same family. Some people with the disease can have a mild course where they are nearly asymptomatic, while others may have severe symptoms that can be fatal. Symptoms commonly begin in the early teens, although onset in childhood or adulthood is possible. Calpainopathy does not affect intelligence or mental function; the primary symptom is progressive muscle weakness of the hip, shoulder, and abdomen. The rate at which the muscles weaken can vary greatly, but many experience progressive weakness to a point where a wheelchair becomes necessary. Other occasional features include enlarged calf muscles, mild shortening and hardening of the muscles leading to rigid joints, and winging of the shoulder blade. Many individuals with calpainopathy live well into adulthood with rare cases of respiratory failure or heart complications being the most common causes of death. Three phenotypes have been identified: pelvofemoral muscular dystrophy (also known as Leyden-Moebius LGMD, where muscle weakness starts in the pelvic girdle), scapulohumeral muscular dystrophy (also known as Erb LGMD, where muscle weakness starts in the shoulder girdle), or hyperCKemia (elevated creatine kinase levels with no known symptoms).
How common is Calpainopathy?
There are numerous types of limb-girdle muscular dystrophy. Autosomal recessive LGMD has an estimated prevalence of 1 in 15,000 individuals. Calpainopathy is thought to account for 10% of all cases of LGMD, though this varies by region. Calpainopathy is more common in Eastern European, Japanese, and Indiana Amish populations, as well as several others.
How is Calpainopathy treated?
There is no cure for calpainopathy and few effective treatments. Physical therapy is often recommended to retain muscle strength and mobility for as long as possible. Stretching, mechanical aids, or surgery may aid in that goal. As muscles deteriorate, a ventilator may be required to aid breathing. Those who develop heart problems should consult with a cardiologist for symptomatic treatments.
What is the prognosis for people with Calpainopathy?
The outlook for a person with calpainopathy varies. Generally, the earlier symptoms begin, the faster they progress. Some people with the disease experience only mild symptoms, and may have near-normal strength. Others with a mild course may remain able to walk for 30 years or more after symptoms appear. People with more severe disease typically become wheelchair-bound as early as 10 years after their diagnosis.