ICD-10 Code G71.21 – Nemaline Myopathy (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G71.21 – Nemaline myopathy
What it is
G71.21 identifies nemaline myopathy, an inherited or acquired muscle disorder marked by weakness of skeletal muscles. It is used when documentation specifically names this diagnosis.
Clinical signs
Typical findings include generalized or proximal muscle weakness, low muscle tone, and delayed motor development. Clinical features vary; refer to documentation for the documented pattern and severity.
When to use this code
Use this code when the provider documents nemaline myopathy, including confirmed pathology or genetic diagnosis. You may also use it when the chart clearly links the patient’s weakness to this condition. Check documentation if the record only says “myopathy” without a specific type.
Do not use for
Do not use this code for unspecified muscle weakness, other hereditary myopathies, or muscular dystrophy unless nemaline myopathy is documented. Do not assume the diagnosis from suspicion alone.
Coding tip
Code G71.21 only when the diagnosis is explicit in the record; if the type of myopathy is unclear, query the provider.