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G10 ICD-10-CM Code: Huntington's disease

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
2 inclusion terms · 7 use-additional codes
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 78 · RxHCC V08 category 160

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 056 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC (MDC 01)
  • MS-DRG 057 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC (MDC 01)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 200 — Friedreich and Other Hereditary Ataxias; Huntington Disease

Other models: CMS-HCC V22 HCC 78 · RxHCC V08 HCC 160

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for G10 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Huntington's chorea
  • Huntington's dementia

Use Additional Code

Supplementary codes the tabular list directs you to add.

Coder workflow for G10

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Use Additional Code — after identifying G10(7 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with G10 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewF02.84, F02.A4, F02.B4, F02.C4, F02.81, F02.A1

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with G10?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewF02.84, F02.A4, F02.B4, F02.C4, F02.81, F02.A1

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Huntington's disease is a billable ICD-10-CM diagnosis code (G10).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (10)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name G10 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 3 Excludes1 notes across 2 chapters: G21 — Secondary parkinsonism, G25.5 — Other chorea, I02 — Rheumatic chorea.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 2 Code First instructions: F02 — Dementia in other diseases classified elsewhere, F06.7 — Mild neurocognitive disorder due to known physiological condition.

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 67 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 056 (MDC 01), DRG 057 (MDC 01).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS006 — Other nervous system disorders (often hereditary or degenerative) (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

G04.1 — Tropical spastic paraplegia, G20.A1 — Parkinson's disease without dyskinesia, without mention of fluctuations, G20.A2 — Parkinson's disease without dyskinesia, with fluctuations, G20.B1 — Parkinson's disease with dyskinesia, without mention of fluctuations, G20.B2 — Parkinson's disease with dyskinesia, with fluctuations, G20.C — Parkinsonism, unspecified, G21.11 — Neuroleptic induced parkinsonism, G21.19 — Other drug induced secondary parkinsonism, G21.2 — Secondary parkinsonism due to other external agents, G21.3 — Postencephalitic parkinsonism, G21.4 — Vascular parkinsonism, G21.8 — Other secondary parkinsonism, G21.9 — Secondary parkinsonism, unspecified, G35.A — Relapsing-remitting multiple sclerosis, G35.B0 — Primary progressive multiple sclerosis, unspecified, G35.B1 — Active primary progressive multiple sclerosis, G35.B2 — Non-active primary progressive multiple sclerosis, G35.C0 — Secondary progressive multiple sclerosis, unspecified, G35.C1 — Active secondary progressive multiple sclerosis, G35.C2 — Non-active secondary progressive multiple sclerosis, +46 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Friedreich and Other Hereditary Ataxias; Huntington Disease) for risk-adjusted payment.

G11.0 — Congenital nonprogressive ataxia, G11.10 — Early-onset cerebellar ataxia, unspecified, G11.11 — Friedreich ataxia, G11.19 — Other early-onset cerebellar ataxia, G11.2 — Late-onset cerebellar ataxia, G11.3 — Cerebellar ataxia with defective DNA repair, G11.4 — Hereditary spastic paraplegia, G11.5 — Hypomyelination - hypogonadotropic hypogonadism - hypodontia, G11.6 — Leukodystrophy with vanishing white matter disease, G11.8 — Other hereditary ataxias, G11.9 — Hereditary ataxia, unspecified, G31.80 — Leukodystrophy, unspecified, G90.B — LMNB1-related autosomal dominant leukodystrophy, G93.42 — Megalencephalic leukoencephalopathy with subcortical cysts, G93.43 — Leukoencephalopathy with calcifications and cysts, G93.44 — Adult-onset leukodystrophy with axonal spheroids

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other nervous system disorders (often hereditary or degenerative)).

E75.10 — Unspecified gangliosidosis, E75.11 — Mucolipidosis IV, E75.19 — Other gangliosidosis, E75.23 — Krabbe disease, E75.25 — Metachromatic leukodystrophy, E75.26 — Sulfatase deficiency, E75.27 — Pelizaeus-Merzbacher disease, E75.28 — Canavan disease, E75.29 — Other sphingolipidosis, E75.4 — Neuronal ceroid lipofuscinosis, G11.0 — Congenital nonprogressive ataxia, G11.1 — Early-onset cerebellar ataxia, G11.10 — Early-onset cerebellar ataxia, unspecified, G11.11 — Friedreich ataxia, G11.19 — Other early-onset cerebellar ataxia, G11.2 — Late-onset cerebellar ataxia, G11.3 — Cerebellar ataxia with defective DNA repair, G11.4 — Hereditary spastic paraplegia, G11.5 — Hypomyelination - hypogonadotropic hypogonadism - hypodontia, G11.6 — Leukodystrophy with vanishing white matter disease, +83 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Dementia”, “Chorea”; these codes share that main term but sit in a different category of the Tabular List.

F10.97 — Alcohol use, unspecified with alcohol-induced persisting dementia (alcoholic), F13.27 — Sedative, hypnotic or anxiolytic dependence with sedative, hypnotic or anxiolytic-induced persisting dementia (in, sedatives, hypnotics or anxiolytics, with dependence), F13.97 — Sedative, hypnotic or anxiolytic use, unspecified with sedative, hypnotic or anxiolytic-induced persisting dementia (in, sedatives, hypnotics or anxiolytics), F18.27 — Inhalant dependence with inhalant-induced dementia (in, inhalants, with dependence), F18.97 — Inhalant use, unspecified with inhalant-induced persisting dementia (in, inhalants), F19.27 — Other psychoactive substance dependence with psychoactive substance-induced persisting dementia (in, psychoactive drug, with dependence), F19.97 — Other psychoactive substance use, unspecified with psychoactive substance-induced persisting dementia (in, psychoactive drug), F44.4 — Conversion disorder with motor symptom or deficit (hysterical), F84.3 — Other childhood disintegrative disorder (infantile, infantilis), F95.8 — Other tic disorders (habit), G20.A1 — Parkinson's disease without dyskinesia, without mention of fluctuations (in, Parkinson's disease), G20.C — Parkinsonism, unspecified (with, Parkinsonism), G25.4 — Drug-induced chorea (drug-induced), G25.5 — Other chorea, G31.01 — Pick's disease (in, Pick's), G31.09 — Other frontotemporal neurocognitive disorder (frontal), G31.83 — Neurocognitive disorder with Lewy bodies (Lewy body), G35.D — Multiple sclerosis, unspecified (in, multiple, sclerosis), I02.0 — Rheumatic chorea with heart involvement (with, heart involvement), I02.9 — Rheumatic chorea without heart involvement (minor), +88 more

Contextual Map

Every relationship of G10 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G10 with these 13 related codes in Claim Check

Hierarchy

Use Additional Code (21)

Referenced by Excludes1 notes

  • G21 — Secondary parkinsonism[Excludes1]: “Huntington's disease (G10)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • G25.5 — Other chorea[Excludes1]: “Huntington's chorea (G10)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • I02 — Rheumatic chorea[Excludes1]: “Huntington's chorea (G10)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code First instructions

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 200 — Friedreich and Other Hereditary Ataxias; Huntington Disease [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,892 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries (10)

  • Chorea (chronic) (gravis) (posthemiplegic) (senile) (spasmodic), hereditary[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Chorea (chronic) (gravis) (posthemiplegic) (senile) (spasmodic), Huntington's[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Chorea (chronic) (gravis) (posthemiplegic) (senile) (spasmodic), progressive, hereditary[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety), in (due to), Huntington's disease or chorea[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety), in (due to), Huntington's disease or chorea, with behavioral disturbance[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, Huntington's[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, Huntington's, with dementia[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Huntington's disease or chorea[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 2 more

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "G10 — Huntington's disease." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/g10-huntingtons-disease

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Huntington's disease

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.