2026 ICD-10-CM Diagnosis Code G12.21Amyotrophic lateral sclerosis

ICD-10-CM Codes›G00–G99›G10-G14›G12

ICD-10-CM G12.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G12.21 is a billable ICD-10-CM diagnosis code for amyotrophic lateral sclerosis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is restricted by the Medicare Code Editor to adult patients (age 15 through 124). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).

Code Identity

ICD-10-CM Code
G12.21
Billable Status
Yes — Valid for Submission
Code Describes
Amyotrophic lateral sclerosis
Short Description
Amyotrophic lateral sclerosis
Same as the full description in the CMS dataset.
Parent Code
G12.2
Motor neuron disease

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG10-G14Systemic atrophies primarily affecting the central nervous system
CategoryG12Spinal muscular atrophy and related syndromes
This CodeG12.21Amyotrophic lateral sclerosis

Code EditsBilling

Medicare Code Editor checks that affect claim validity for G12.21.

Adult diagnoses
The Medicare Code Editor detects inconsistencies in adult cases by checking a patient's age and any diagnosis on the patient's record. The adult code edits apply to patients age range is 15–124 years inclusive (e.g., senile delirium, mature cataract).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Amyotrophic lateral sclerosis
  • Amyotrophic lateral sclerosis plus syndrome
  • Amyotrophic lateral sclerosis type 1
  • Amyotrophic lateral sclerosis type 10
  • Amyotrophic lateral sclerosis type 3
  • Amyotrophic lateral sclerosis type 4
  • Amyotrophic lateral sclerosis type 6
  • Amyotrophic lateral sclerosis type 7
  • Amyotrophic lateral sclerosis type 8
  • Amyotrophic lateral sclerosis type 9
  • Amyotrophic lateral sclerosis with autonomic dysfunction
  • Amyotrophic lateral sclerosis with cerebellar dysfunction
  • Amyotrophic lateral sclerosis with dementia
  • Amyotrophic lateral sclerosis with frontotemporal dementia
  • Amyotrophic lateral sclerosis with multiple system atrophy
  • Amyotrophic lateral sclerosis with parkinsonism
  • Amyotrophic lateral sclerosis with spinocerebellar ataxia
  • Amyotrophic lateral sclerosis, parkinsonism, dementia complex
  • Amyotrophic lateral sclerosis, parkinsonism, dementia complex of Kii Peninsula
  • Amyotrophic lateral sclerosis, parkinsonism, dementia complex of West New Guinea
  • Autosomal dominant amyotrophic lateral sclerosis type 1
  • Autosomal recessive amyotrophic lateral sclerosis type 1
  • Juvenile amyotrophic lateral sclerosis
  • Juvenile amyotrophic lateral sclerosis type 2
  • Juvenile amyotrophic lateral sclerosis type 5
  • Multiple system atrophy
  • Restrictive lung disease
  • Restrictive lung disease due to amyotrophic lateral sclerosis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Amyotrophia, amyotrophy, amyotrophic
      • lateral sclerosis
    • Atrophy, atrophic(of)
      • Duchenne-Aran
    • Atrophy, atrophic(of)
      • muscle, muscular (diffuse) (general) (idiopathic) (primary)
        • Duchenne-Aran
    • Atrophy, atrophic(of)
      • muscle, muscular (diffuse) (general) (idiopathic) (primary)
        • progressive (bulbar)
    • Atrophy, atrophic(of)
      • muscle, muscular (diffuse) (general) (idiopathic) (primary)
        • spinal
          • Aran-Duchenne
    • Disease, diseased
      • motor neuron (bulbar) (mixed type) (spinal)
        • amyotrophic lateral sclerosis
    • Duchenne-Aran muscular atrophy
    • Paralysis, paralytic(complete) (incomplete)
      • amyotrophic
    • Paralysis, paralytic(complete) (incomplete)
      • muscle, muscular NEC
        • progressive
    • Paralysis, paralytic(complete) (incomplete)
      • spinal (cord)
        • progressive
    • Sclerosis, sclerotic
      • amyotrophic (lateral)
    • Sclerosis, sclerotic
      • lateral (amyotrophic) (descending) (spinal)
    • Sclerosis, sclerotic
      • spinal (cord) (progressive)
        • lateral (amyotrophic)

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS006
Other nervous system disorders (often hereditary or degenerative)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Amyotrophic Lateral Sclerosis

    a degenerative disorder affecting upper motor neurons in the brain and lower motor neurons in the brain stem and spinal cord. disease onset is usually after the age of 50 and the process is usually fatal within 3 to 6 years. clinical manifestations include progressive weakness, atrophy, fasciculation, hyperreflexia, dysarthria, dysphagia, and eventual paralysis of respiratory function. pathologic features include the replacement of motor neurons with fibrous astrocytes and atrophy of anterior spinal nerve roots and corticospinal tracts. (from adams et al., principles of neurology, 6th ed, pp1089-94)

  • Multiple System Atrophy

    a syndrome complex composed of three conditions which represent clinical variants of the same disease process: striatonigral degeneration; shy-drager syndrome; and the sporadic form of olivopontocerebellar atrophies. clinical features include autonomic, cerebellar, and basal ganglia dysfunction. pathologic examination reveals atrophy of the basal ganglia, cerebellum, pons, and medulla, with prominent loss of autonomic neurons in the brain stem and spinal cord. (from adams et al., principles of neurology, 6th ed, p1076; baillieres clin neurol 1997 apr;6(1):187-204; med clin north am 1999 mar;83(2):381-92)

  • Restrictive Lung Disease

    decreased lung volume and inadequate ventilation due to parenchymal lung disorders (e.g., interstitial pulmonary fibrosis) or extrapulmonary disorders (e.g., scoliosis). patients present with shortness of breath and cough.

Patient EducationClinical

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a nervous system disease that attacks nerve cells called neurons in your brain and spinal cord. These neurons transmit messages from your brain and spinal cord to your voluntary muscles - the ones you can control, like in your arms and legs. At first, this causes mild muscle problems.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G12.21 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
335.20 Amyotrophic sclerosis
Approximate The match is approximate rather than exact.
ICD-9-CM
335.21 Prog muscular atrophy
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G12.21Overview

Is G12.21 (Motor neuron disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report amyotrophic lateral sclerosis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Who can G12.21 be reported for?

The Medicare Code Editor checks amyotrophic lateral sclerosis against patient demographics: this code is intended for adult patients (age 15 through 124). Claims outside these limits are flagged as inconsistent.

What is the ICD-9 equivalent of G12.21?

Under the General Equivalence Mappings, amyotrophic lateral sclerosis converts to ICD-9-CM 335.20 (amyotrophic sclerosis) and 335.21 (prog muscular atrophy). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.