ICD-10 G10
Billable / Specific HCC v28: 78 CCHuntington's disease
About ICD-10-CM G10
ICD-10-CM code G10 represents Huntington's disease. This is a billable/specific code in the Nervous System chapter (block G10). The 2026 edition of ICD-10-CM G10 became effective on October 1, 2025.
Coding Tips for G10
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G10 is a CMS-HCC v28 risk-adjustment code (category 78). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
G10 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under G10. Per CMS ICD-10-CM Tabular 2026.
- Huntington's chorea
- Huntington's dementia
Use Additional Code
When coding G10, also report these additional codes when applicable.
- 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-)
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, CC
codes Huntington's disease. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for G10
Local Coverage Determinations (LCDs) from CMS MACs that list G10 as a covered diagnosis.
Showing top 10 of 404 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G10.
2 Cigna
5 Medicare
CPT Codes Commonly Billed with G10
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 95857 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92512 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92617 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92520 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92630 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92612 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92606 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92618 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 92650 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
- 31579 CMS LCD: Billing and Coding: Outpatient Speech Language Pathology CMS LCD
Convert G10 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| G10 | 3334 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To G10
Other codes in section G10-G14 (Systemic atrophies primarily affecting the central nervous system).
ICD-10 G10, Billing FAQ
Is ICD-10 code G10 billable? +
Yes, G10 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to G10? +
ICD-10 G10 includes: Huntington's chorea; Huntington's dementia.
Does G10 affect Medicare Advantage HCC risk adjustment? +
Yes. G10 maps to CMS-HCC v28 category 78. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is G10 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with G10? +
Procedures frequently paired with G10 include: 95857, 92512, 92617, 92520, 92630.
What ICD-9 codes does G10 map to? +
Per CMS GEMs, G10 maps to ICD-9 codes: 3334. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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