The etiology is unknown. Some cases of SLONM have been comorbid with HIV infection, and others with immune disorders, and so both a viral trigger and an autoimmune disorder have been considered candidate etiologies. The monoclonal gammopathy of unknown significance (MGUS) associated with a worse prognosis also argues for an immune disorder. On electron microscopy,<unk>  bodies within the affected muscle fibers may be found. These bodies are sometimes crisply rod-shaped, but can also be irregular and punctate. The rods may be found alongside atrophic muscle fibers, and may be seen arising from the thickened Z-discs of the sarcolemmae. Affected fibers may be vacuolated or lobulated.
Sporadic late-onset nemaline myopathy
Hereditary motor and sensory neuropathy with proximal dominance
Acquired non-inflammatory myopathy
Desmin-related myofibrillar myopathy
Myopathy, X-linked, with excessive autophagy
Statin-associated autoimmune myopathy
Lethal arthrogryposis with anterior horn cell disease
Thyrotoxic myopathy