2026 ICD-10-CM Diagnosis Code G11.2Late-onset cerebellar ataxia

ICD-10-CM Codes›G00–G99›G10-G14›G11

ICD-10-CM G11.2
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G11.2 is a billable ICD-10-CM diagnosis code for late-onset cerebellar ataxia. 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
G11.2
Billable Status
Yes — Valid for Submission
Code Describes
Late-onset cerebellar ataxia
Short Description
Late-onset cerebellar ataxia
Same as the full description in the CMS dataset.
Parent Code
G11
Hereditary ataxia

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG10-G14Systemic atrophies primarily affecting the central nervous system
CategoryG11Hereditary ataxia
This CodeG11.2Late-onset cerebellar ataxia

Code EditsBilling

Medicare Code Editor checks that affect claim validity for G11.2.

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.

  • Adult-onset autosomal recessive cerebellar ataxia
  • Autosomal recessive cerebellar ataxia, psychomotor delay syndrome
  • Azorean disease
  • Azorean disease, type I
  • Azorean disease, type II
  • Azorean disease, type III
  • Azorean disease, type IV
  • Episodic ataxia
  • Hereditary cerebellar atrophy
  • Late onset cerebellar ataxia
  • Marie's cerebellar ataxia
  • Periodic ataxia
  • Progressive cerebellar ataxia
  • Progressive cerebellar ataxia with hypogonadism
  • Progressive cerebellar ataxia with palatal myoclonus
  • Progressive spinocerebellar ataxia with decreased tendon reflexes
  • PUM1-related cerebellar ataxia
  • Spinocerebellar ataxia type 45
  • Spinocerebellar ataxia type 46
  • Sporadic adult-onset ataxia of unknown etiology

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.

    • Ataxia, ataxy, ataxic
      • cerebellar (hereditary)
        • late-onset (Marie's)
    • Ataxia, ataxy, ataxic
      • Marie's (cerebellar) (heredofamilial) (late- onset)
    • Ataxia, ataxy, ataxic
      • Sanger-Brown's (hereditary)
    • Marie's
      • cerebellar ataxia (late-onset)
    • Sanger-Brown ataxia

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

Patient EducationClinical

Cerebellar Disorders

When you play the piano or hit a tennis ball you are activating the cerebellum. The cerebellum is the area of the brain that controls coordination and balance. Problems with the cerebellum include:

Read the full article at MedlinePlus

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

Convert G11.2 to ICD-9-CMHistory

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

ICD-9-CM
334.2 Primary cerebellar degen
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 G11.2Overview

Is G11.2 (Hereditary ataxia) a billable code?

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

Who can G11.2 be reported for?

The Medicare Code Editor checks late-onset cerebellar ataxia 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 G11.2?

Under the General Equivalence Mappings, late-onset cerebellar ataxia converts to ICD-9-CM 334.2 (primary cerebellar degen). 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.