Landouzy–Dejerine muscular dystrophy

Landouzy–Dejerine Muscular Dystrophy

Landouzy–Dejerine muscular dystrophy, also known as facioscapulohumeral muscular dystrophy (FSHD), is a genetic muscle disorder characterized by progressive skeletal muscle weakness. It primarily affects the muscles of the face (facio-), shoulder blades (scapulo-), and upper arms (humeral). This condition is named after the French neurologists Louis Théophile Joseph Landouzy and Joseph Jules Dejerine, who first described it in the late 19th century.

Clinical Features

The clinical presentation of Landouzy–Dejerine muscular dystrophy is variable, but it typically includes the following features:

• Facial Weakness: Patients often exhibit difficulty with facial expressions, such as smiling or closing their eyes tightly. This is due to weakness of the facial muscles.
• Scapular Winging: Weakness of the shoulder girdle muscles leads to scapular winging, where the shoulder blades protrude abnormally.
• Upper Arm Weakness: The muscles of the upper arms are affected, leading to difficulty in lifting objects or raising the arms.
• Asymmetric Muscle Involvement: Unlike some other muscular dystrophies, FSHD often presents with asymmetric muscle involvement.
• Hearing Loss: Some individuals may experience sensorineural hearing loss.
• Retinal Vascular Disease: There can be an association with retinal vascular abnormalities, although this is less common.

Genetics

Landouzy–Dejerine muscular dystrophy is most commonly associated with a genetic defect on chromosome 4q35. The disorder is typically inherited in an autosomal dominant pattern, meaning a single copy of the altered gene in each cell is sufficient to cause the disorder.

The genetic defect involves a contraction of the D4Z4 repeat array on chromosome 4. In healthy individuals, this region contains 11-100 repeat units, whereas in individuals with FSHD, the number of repeats is reduced to 1-10 units. This contraction leads to the inappropriate expression of the DUX4 gene, which is believed to be toxic to muscle cells.

Diagnosis

Diagnosis of Landouzy–Dejerine muscular dystrophy is based on clinical evaluation, family history, and genetic testing. Muscle biopsy and electromyography (EMG) may also be used to assess muscle function and structure.

Management

There is currently no cure for Landouzy–Dejerine muscular dystrophy. Management focuses on symptomatic treatment and supportive care:

• Physical Therapy: To maintain muscle strength and flexibility.
• Orthotic Devices: To support weakened muscles and improve mobility.
• Surgical Interventions: In some cases, surgery may be performed to correct scapular winging or other deformities.
• Hearing Aids: For those with hearing loss.

Prognosis

The progression of Landouzy–Dejerine muscular dystrophy is variable. Some individuals experience mild symptoms and maintain a normal lifespan, while others may have more severe muscle weakness and disability.

Also see

• Muscular dystrophy
• Genetic disorders
• Neuromuscular disease
• Autosomal dominant disorder