2026 ICD-10-CM Diagnosis Code G23.3Hypomyelination with atrophy of the basal ganglia and cerebellum

ICD-10-CM Codes›G00–G99›G20-G26›G23

ICD-10-CM G23.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G23.3 is a billable ICD-10-CM diagnosis code for hypomyelination with atrophy of the basal ganglia and cerebellum. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). 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
G23.3
Billable Status
Yes — Valid for Submission
Code Describes
Hypomyelination with atrophy of the basal ganglia and cerebellum
Short Description
Hypomyelination with atrophy of basal ganglia and cerebellum
Parent Code
G23
Other degenerative diseases of basal ganglia

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG20-G26Extrapyramidal and movement disorders
CategoryG23Other degenerative diseases of basal ganglia
This CodeG23.3Hypomyelination with atrophy of the basal ganglia and cerebellum

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • H-ABC
  • TUBB4A-related neurologic disorders

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.

    • Disorder(of)
      • neurological NEC
        • TUBB4A-related
    • H-ABC(hypomyelination with atrophy of the basal ganglia and cerebellum)
    • Hypomyelination with atrophy of the basal ganglia and cerebellum(H-ABC)

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

Code History & ChangesHistory

Replacement G23.3 replaces the following previously assigned code(s):

  • G23.8 - Other specified degenerative diseases of basal ganglia
FY 2024AddedAdded to the ICD-10-CM code setEffective October 1, 2023.
FY 2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G23.3Overview

Is G23.3 (Other degenerative diseases of basal ganglia) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hypomyelination with atrophy of the basal ganglia and cerebellum on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

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.