2026 ICD-10-CM Diagnosis Code G10Huntington's disease
ICD-10-CM Codes›G00–G99›G10-G14›G10
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 200
- Chronic Condition
G10 is a billable ICD-10-CM diagnosis code for Huntington's disease. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 56 through 57. 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 67 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).
For Medicare Advantage risk adjustment, G10 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 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
G10 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 2026.
Source: CMS Payment Year 2026 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.
- Akinetic-rigid form of Huntington's disease
- Altered behavior in Huntington's dementia
- Atrophy of caudate nucleus
- Chorea co-occurrent and due to Huntington disease-like condition
- Dementia due to genetic disease
- Dementia due to Huntington chorea
- Huntington disease-like 2
- Huntington disease-like syndrome
- Huntington's chorea
- Juvenile onset Huntington's disease
- Late onset Huntington's disease
- Progressive chorea
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Huntington's chorea
- Huntington's dementia
Use Additional Code
- code, if applicable, to identify:
- dementia with anxiety F02.84 F02.A4 F02.B4 F02.C4
- dementia with behavioral disturbance F02.81 F02.A1 F02.B1 F02.C1
- dementia with mood disturbance F02.83 F02.A3 F02.B3 F02.C3
- dementia with psychotic disturbance F02.82 F02.A2 F02.B2 F02.C2
- dementia without behavioral disturbance F02.80 F02.A0 F02.B0 F02.C0
- mild neurocognitive disorder due to known physiological condition F06.7
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Chorea (chronic) (gravis) (posthemiplegic) (senile) (spasmodic) G25.5
hereditary G10
Huntington's G10
hereditary G10
Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) F03.90
Huntington's disease or chorea See Also: Dementia, in, diseases specified elsewhere; G10
with behavioral disturbance See Also: Dementia, in, diseases specified elsewhere; G10
Disease, diseased See Also: Syndrome;
Huntington's G10
with dementia See Also: Dementia, in, diseases specified elsewhere; G10
Huntington's disease or chorea G10
with dementia See Also: Dementia, in, diseases specified elsewhere; G10
with behavioral disturbance See Also: Dementia, in, diseases specified elsewhere; G10
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Huntington's Disease
Huntington's disease (HD) is an inherited disease that causes certain nerve cells in the brain to waste away. People are born with the defective gene, but symptoms usually don't appear until middle age. Early symptoms of HD may include uncontrolled movements, clumsiness, and balance problems.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G10 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G10Overview
What is the ICD-10 code for Huntington's disease?
The ICD-10-CM code for Huntington's disease is G10. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is G10 (Huntington's disease) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report Huntington's disease on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does G10 group to?
When Huntington's disease is the principal diagnosis on an inpatient stay, it groups to MS-DRG 56, 57, with relative weights from 1.2956 to 2.3231 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G10 a CC or MCC?
CMS lists G10 as a CC (complication or comorbidity) for FY 2026. 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 67 closely related codes in its exclusion list.
What is the ICD-9 equivalent of G10?
Under the General Equivalence Mappings, Huntington's disease converts to ICD-9-CM 333.4 (Huntington's chorea). The mapping is a direct match.
What HCC is G10?
G10 (Huntington's disease) 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 2026. It mapped to HCC 78 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 160.
Does G10 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G10 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.
