Nemaline myopathy

This code identifies a rare, congenital, and often slowly progressive neuromuscular disorder characterized by the presence of rod-like structures (nemaline bodies) within muscle fibers. It primarily manifests as muscle weakness, hypotonia, and sometimes respiratory insufficiency, varying in severity from mild to severe. The condition is typically genetic in origin, affecting skeletal muscles throughout the body.

Use this code for patients diagnosed with nemaline myopathy based on clinical presentation, muscle biopsy findings demonstrating nemaline bodies, and often genetic testing confirming a pathogenic variant. It is appropriate for initial diagnosis and subsequent encounters for ongoing management of the condition. Documentation should clearly state the diagnosis of nemaline myopathy.

• Ensure documentation specifies "nemaline myopathy" and not a more general myopathy, as other congenital myopathies have distinct codes.
• Consider additional codes for associated symptoms or complications, such as respiratory failure (J96.-) or scoliosis (M41.-), if present and documented.
• Genetic testing results, if available, can support the diagnosis but are not strictly required for coding if clinical and biopsy findings are definitive.