OBSOLETE: Acquired rod-body myopathy

Acquired rod-body myopathy (also known as acquired nemaline myopathy) is a rare muscle disorder characterized by the presence of rod-shaped structures (nemaline bodies or rods) within muscle fibers, occurring in individuals without a prior genetic predisposition to nemaline myopathy. Unlike the hereditary forms of nemaline myopathy, this condition develops later in life and is often associated with underlying conditions such as HIV infection, monoclonal gammopathy, autoimmune disorders, or other systemic illnesses. The disease primarily affects skeletal muscles, leading to progressive muscle weakness that can involve proximal limb muscles, respiratory muscles, and sometimes bulbar muscles controlling swallowing and speech. Key symptoms include progressive generalized or proximal muscle weakness, difficulty breathing due to respiratory muscle involvement, dysphagia, and exercise intolerance. Muscle biopsy reveals characteristic nemaline rods within muscle fibers, which is essential for diagnosis. The condition can be rapidly progressive and life-threatening, particularly when respiratory failure develops. This Orphanet entry is marked as OBSOLETE, indicating it may have been reclassified or merged into another disease category within the Orphanet classification system. Treatment is primarily directed at the underlying associated condition when identified (e.g., treating HIV infection or monoclonal gammopathy), along with supportive care including respiratory support, physical therapy, and in some cases immunosuppressive therapy such as intravenous immunoglobulin (IVIG) or corticosteroids. Outcomes vary depending on the underlying cause and the severity of muscle and respiratory involvement.

Inheritance

Sporadic

Usually appears on its own, not inherited from a parent

Age of Onset

Adult

Begins in adulthood (age 18 or older)

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Source: ClinicalTrials.gov · synced daily · phases, status, and PI names normalized at ingest

Source: NPI Registry + PubMed · trial PI roles cross-referenced with ClinicalTrials.gov · ranked by match score (publications + PI activity + community signal)

Source: NORD Rare Disease Centers + NIH Undiagnosed Diseases Network (UDN) · centers verified active within last 12 months

Source: PubMed + NIH RePORTER + openFDA + clinical-journal RSS · last 30 days · disease-tagged at ingest by AI extraction with human QC

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