G11.3 ICD-10-CM Code: Cerebellar ataxia with defective DNA repair
G11.3 maps to CMS-HCC V28 200. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Systemic atrophies primarily affecting the central nervous system (G10-G14)
G11.3
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceCerebellar ataxia with defective DNA repair
Cerebellar ataxia with defective DNA repair is a rare genetic disorder where the body cannot properly repair DNA damage, leading to progressive neurological problems and increased cancer risk.
Buddy Insight
Cerebellar ataxia with defective DNA repair, most commonly ataxia-telangiectasia, is a rare genetic disorder with multisystem implications including progressive neurodegeneration, immunodeficiency, and dramatically increased cancer risk.
CMS-HCC V28
MappedHCC 200
Code-level coefficient reference
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 119
Code-level coefficient reference
ESRD/PACE
MappedHCC 72
Code-level coefficient reference
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
Official- Ataxia telangiectasia [Louis-Bar]
Excludes 2
Official- Cockayne's syndrome (Q87.19)
- other disorders of purine and pyrimidine metabolism (E79.-)
- xeroderma pigmentosum (Q82.1)
- certain conditions originating in the perinatal period (P04-P96)Inherited from G00-G99, G11
- certain infectious and parasitic diseases (A00-B99)Inherited from G00-G99, G11
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from G00-G99, G11
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from G00-G99, G11
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from G00-G99, G11
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from G00-G99, G11
- neoplasms (C00-D49)Inherited from G00-G99, G11
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from G00-G99, G11
- cerebral palsy (G80.-)Inherited from G00-G99, G11
- hereditary and idiopathic neuropathy (G60.-)Inherited from G00-G99, G11
- metabolic disorders (E70-E88)Inherited from G00-G99, G11
Related Codes
Includes
OfficialNo Includes notes are included in this display for G11.3. Check the code and parent instructions in the Code Book.
Excludes 1
OfficialNo Excludes 1 notes are included in this display for G11.3. Check the code and parent instructions in the Code Book.
Code First
OfficialNo Code First sequencing instructions are included in this display for G11.3. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for G11.3. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for G11.3. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is G11.3 an HCC code?
Yes. G11.3 (Cerebellar ataxia with defective DNA repair) maps to HCC 200, Friedreich and Other Hereditary Ataxias; Huntington Disease under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.279. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: G11.3 is billable and maps to V28 HCC 200, Friedreich and Other Hereditary Ataxias; Huntington Disease. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- G11.3
- Description
- Cerebellar ataxia with defective DNA repair
- HCC (V28)
- HCC 200 — Friedreich and Other Hereditary Ataxias; Huntington Disease
- RAF reference coefficient
- 0.279
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work G11.3 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for G11.3
For G11.3, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Coder workflow notes
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What This Code Means
G11.3 is the ICD-10-CM diagnosis code for cerebellar ataxia with defective dna repair. Cerebellar ataxia with defective DNA repair is a rare genetic disorder where the body cannot properly repair DNA damage, leading to progressive neurological problems and increased cancer risk. G11.3 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering systemic atrophies primarily affecting the central nervous system (g10-g14).
Under the CMS-HCC V28 risk adjustment model, G11.3 maps to Friedreich and Other Hereditary Ataxias; Huntington Disease (HCC 200) with a source-labeled community, non-dual, aged reference coefficient of 0.279. No V24 mapping is shown for G11.3; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
Document the specific DNA repair defect if identified (e.g., ataxia-telangiectasia, xeroderma pigmentosum). For G11.3, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for G11.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the specific DNA repair defect if identified (e.g., ataxia-telangiectasia, xeroderma pigmentosum)
- •Code any associated malignancies or immunodeficiency separately
Clinical Significance
Cerebellar ataxia with defective DNA repair, most commonly ataxia-telangiectasia, is a rare genetic disorder with multisystem implications including progressive neurodegeneration, immunodeficiency, and dramatically increased cancer risk. This diagnosis signals extremely high healthcare complexity and cost, requiring coordination across neurology, immunology, and oncology services.
Documentation Requirements
- ✓Specific DNA repair defect identified (ataxia-telangiectasia, xeroderma pigmentosum, Cockayne syndrome)
- ✓Genetic testing results confirming the DNA repair deficiency
- ✓Progressive cerebellar ataxia on neurological examination
- ✓Immunological workup results (immunoglobulin levels, lymphocyte subsets)
- ✓Cancer screening and surveillance plan documented
- ✓Associated telangiectasias or skin findings if present
Excludes 2, Not included here, may code separately
Commonly Confused Codes
- •G11.19: Other early-onset cerebellar ataxia: use when early-onset ataxia lacks DNA repair component
- •D82.0: Wiskott-Aldrich syndrome: another immunodeficiency with neurological features but different genetic basis
- •G11.0: Congenital nonprogressive ataxia: ataxia-telangiectasia is progressive, not stable
- •D81.9: Combined immunodeficiency, unspecified: captures the immune component but misses the ataxia