Sporadic Late-Onset Nemaline Myopathy: Current Landscape

Area of Science:

• Neurology
• Muscle Diseases
• Immunology

Background:

• Sporadic late-onset nemaline myopathy (SLONM) is a rare acquired adult-onset muscle disorder.
• It is characterized by nemaline rod accumulation in muscle fibers.
• SLONM can be associated with monoclonal gammopathy or HIV infection.

Purpose of the Study:

• To review current knowledge on the presentation, pathophysiology, and management of SLONM.
• To highlight recent findings that elucidate disease mechanisms.
• To differentiate SLONM from inherited nemaline myopathies.

Main Methods:

• Review of current literature on SLONM.
• Analysis of histological, proteomic, and transcriptomic data.
• Evaluation of treatment responses.

Main Results:

• SLONM presents as progressive proximal and axial weakness, sometimes mimicking muscular dystrophy.
• Pathophysiology may involve autoimmune mechanisms or hematological neoplasia.
• Recent studies identified molecular alterations distinguishing SLONM from inherited forms.
• Many patients respond to immunoglobulins, chemotherapy, or stem cell transplant.

Conclusions:

• SLONM is a treatable myopathy with unclear etiology and pathomechanisms.
• High clinical suspicion is crucial to reduce diagnostic delay.
• Distinguishing SLONM from inherited nemaline myopathies is important for appropriate management.