2027 ICD-10-CM Diagnosis Code G11.2Late-onset cerebellar ataxia
ICD-10-CM Codes›G00–G99›G10-G14›G11
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 200
- Chronic Condition
G11.2 is a billable ICD-10-CM diagnosis code for late-onset cerebellar ataxia. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 58 through 60. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 175 closely related codes. 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).
For Medicare Advantage risk adjustment, G11.2 maps to CMS-HCC Category 200 (Friedreich and Other Hereditary Ataxias; Huntington Disease) under the V28 model, adding a risk factor of about 0.279 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for G11.2.
Medicare Risk Adjustment (HCC)Billing
G11.2 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
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
- 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
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G11.2: its own notes plus those printed at G11 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G11.2, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming G11.2: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Code HistoryHistory
Questions About G11.2Overview
What is the ICD-10 code for late-onset cerebellar ataxia?
The ICD-10-CM code for late-onset cerebellar ataxia is G11.2 (sometimes written as G112). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
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, 2026 through September 30, 2027.
What MS-DRG does G11.2 group to?
When late-onset cerebellar ataxia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 60, 58, 59, with relative weights from 0.9248 to 1.8430 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G11.2 a CC or MCC?
CMS lists G11.2 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 175 closely related codes in its exclusion list.
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 HCC is G11.2?
G11.2 (late-onset cerebellar ataxia) maps to CMS-HCC Category 200 (Friedreich and Other Hereditary Ataxias; Huntington Disease), commonly written as HCC 200, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does G11.2 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G11.2 adds a risk adjustment factor of about 0.279 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.000 to 0.428 depending on the payment segment). HCC 200 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 200 category page.
