Limb-girdle muscular dystrophy, type 2C

Alternate names

Limb-girdle muscular dystrophy with gamma-sarcoglycan deficiency; Gamma-sarcoglycanopathy; LGMD2C; Muscular dystrophy, Duchenne-like; Duchenne-like muscular dystrophy, autosomal recessive, type 1; DMDA1; Adhalin deficiency, secondary; DMDA; Severe childhood autosomal recessive muscular dystrophy, North African type; Maghrebian myopathy; Autosomal recessive limb-girdle muscular dystrophy type 2C; Limb-girdle muscular dystrophy due to gamma-sarcoglycan deficiency; Gamma-sarcoglycan-related limb-girdle muscular dystrophy R5; Gamma-sarcoglycan-related LGMD R5; LGMD due to gamma-sarcoglycan deficiency; LGMD type 2C; Limb-girdle muscular dystrophy type 2C

Definition

Limb-girdle muscular dystrophy type 2C (LGMD2C) is a genetic condition that affects the voluntary muscles around the hips and shoulders. This condition belongs to a group of muscle disorders called limb-girdle muscular dystrophies, which are characterized by progressive loss of muscle bulk and symmetrical weakening of voluntary muscles.

Onset

Symptoms of LGMD2C usually appear around 6-8 years of age, may be mild or severe, and can progress to loss of the ability to walk by 12-16 years.

Cause

LGMD2C is caused by mutations in the SGCG gene.

Inheritance

Autosomal recessive inheritance, a 25% chance

It is inherited in an autosomal recessive manner.

Signs and symptoms

Symptoms may additionally include: enlargement (hypertrophy) of the calf muscle and tongue, diseases of the heart muscle (cardiomyopathy), and respiratory abnormalities.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 30%-79% of people have these symptoms

• Abnormal macrophage morphology
• Broad-based gait(Wide based walk)
• Calf muscle hypertrophy(Increased size of calf muscles)
• Calf muscle pseudohypertrophy
• Difficulty climbing stairs(Difficulty walking up stairs)
• Difficulty running
• Elevated serum creatine kinase(Elevated blood creatine phosphokinase)
• EMG: myopathic abnormalities
• EMG: myotonic discharges
• EMG: myotonic runs
• EMG: positive sharp waves
• Frequent falls
• Increased endomysial connective tissue
• Increased variability in muscle fiber diameter
• Lumbar hyperlordosis(Excessive inward curvature of lower spine)
• Macroglossia(Abnormally large tongue)
• Right ventricular hypertrophy
• Scapular winging(Winged shoulder blade)
• Upper limb muscle weakness(Decreased arm strength)
• Waddling gait('Waddling' gait)

5%-29% of people have these symptoms

• Achilles tendon contracture(Shortening of the achilles tendon)
• Gowers sign
• Left ventricular systolic dysfunction
• Long face(Elongation of face)
• Neck flexor weakness(Neck flexion weakness)
• Scoliosis
• Tip-toe gait(Walking on tiptoes)

Diagnosis

• The limb-girdle muscular dystrophies typically show degeneration/regeneration (dystrophic changes) on muscle biopsy, which is usually associated with elevated serum creatine kinase concentration.
• For any male or female suspected of having limb-girdle muscular dystrophy, it is necessary to first rule out an X-linked dystrophinopathy.
• Biochemical testing (i.e., protein testing by immunostaining or immunblotting) performed on a muscle biopsy can establish the diagnosis of the following LGMD types: sarcoglycanopathy, calpainopathy, dysferlinopathy, and O-linked glycosylation defects (also known as dystroglycanopathy).
• In some cases, demonstration of complete or partial deficiencies for any particular protein can then be followed by mutation studies of the corresponding gene.
• Pathogenic variants in a number of genes have been associated with types of LGMD.[1].

Treatment

There is no specific treatment for LGMD2C. Management of the condition is based on each person's symptoms and may include:

• Weight control to avoid obesity
• Physical therapy and stretching exercises to promote mobility and prevent contractures
• Use of mechanical aids such as canes, walkers, orthotics, and wheelchairs as needed to help ambulation and mobility
• Monitoring and surgical intervention as needed for orthopedic complications such as foot deformity and scoliosis
• Monitoring of respiratory function and use of respiratory aids when indicated
• Monitoring for evidence of diseases of the heart muscle (cardiomyopathy)
• Social and emotional support and stimulation to maximize a sense of social involvement and productivity and to reduce the sense of social isolation common in these disorders