The muscles most affected are those closest to the body (proximal muscles), specifically the muscles of the shoulders, upper arms, pelvic area, and thighs. Eventually, however, all skeletal muscles are affected.
The severity, age of onset, and features of LGMD vary among the many subtypes. Signs and symptoms may first appear at any age and generally worsen with time, although in some cases they remain mild. However, within each LGMD subtype, the severity, age of onset, and features demonstrate a high degree of consistency.
In the early stages of LGMD, affected individuals may have an unusual walking gait, such as waddling or walking on the balls of their feet, and may also have difficulty running. They may need to use their arms to press themselves up from a squatting position because of their weak thigh muscles. As the condition progresses, people with LGMD eventually require wheelchair assistance.
Muscle wasting may cause changes in posture or in the appearance of the shoulder, back, and arm. In particular, weak shoulder muscles tend to make the shoulder blades (scapulae) “stick out” from the back, a sign known as scapular winging. Affected individuals may also have an abnormally curved lower back (lordosis) or a spine that curves to the side (scoliosis). Some develop joint stiffness (contractures) that can restrict movement in their hips, knees, ankles, or elbows. Overgrowth (hypertrophy) of the calf muscles occurs in some people with LGMD.
Weakening of the heart muscle (cardiomyopathy) occurs in some forms of LGMD, most notably the sarcoglycanopathies (LGMD2C, LGMD2D, LGMD2E, and LGMD2F) and dysferlinopathy (LGMD2B). Some affected individuals experience mild to severe breathing problems related to the weakness of muscles needed for breathing. In some cases, the breathing problems are severe enough that affected individuals need to use a machine to help them breathe (mechanical ventilation). Death resulting from cardiopulmonary insufficiency can occur before age 30 in some subtypes.