2027 ICD-10-CM Diagnosis Code G11.8Other hereditary ataxias
ICD-10-CM Codes›G00–G99›G10-G14›G11
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 200
- Chronic Condition
G11.8 is a billable ICD-10-CM diagnosis code for other hereditary ataxias. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).
For Medicare Advantage risk adjustment, G11.8 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
Medicare Risk Adjustment (HCC)Billing
G11.8 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.
- 4H leukodystrophy
- Abnormal saccadic eye movement
- Acute hepatic failure
- Acute infantile liver failure, cerebellar ataxia, peripheral sensory motor neuropathy syndrome
- Arts syndrome
- Ataxia pancytopenia syndrome
- Ataxia, photosensitivity, short stature syndrome
- Autosomal dominant cerebellar ataxia type 2
- Autosomal recessive cerebellar ataxia Beauce type
- Autosomal recessive cerebellar ataxia due to CWF19L1 deficiency
- Autosomal recessive cerebellar ataxia with saccadic intrusion syndrome
- Autosomal recessive cerebellar ataxia, epilepsy, intellectual disability syndrome due to WWOX deficiency
- Autosomal recessive cerebellar ataxia, pyramidal signs, nystagmus, oculomotor apraxia syndrome
- Autosomal recessive cerebelloparenchymal disorder type 3
- Autosomal recessive spinocerebellar ataxia, blindness, deafness syndrome
- Bailey-Cushing syndrome
- CAMOS syndrome
- Cerebellar ataxia Cayman type
- Cerebellar ataxia, intellectual disability, oculomotor apraxia, cerebellar cysts syndrome
- CLCN2-related leukoencephalopathy
- Congenital atrophy of optic nerve
- Congenital cerebellar ataxia due to RNU12 mutation
- Congenital non-progressive ataxia
- Episodic ataxia
- Episodic ataxia type 1
- Episodic ataxia type 2
- Episodic ataxia type 3
- Episodic ataxia type 4
- Episodic ataxia type 5
- Episodic ataxia type 6
- Episodic ataxia with slurred speech
- Finding of intelligibility of articulation
- Intellectual disability, hyperkinetic movement, truncal ataxia syndrome
- Jervis' syndrome
- Late tooth eruption
- Leukoencephalopathy, ataxia, hypodontia, hypomyelination syndrome
- Mitochondrial myopathy, cerebellar ataxia, pigmentary retinopathy syndrome
- Neuhauser Eichner Opitz syndrome
- Neurodevelopmental delay, intellectual disability, ataxia, feeding difficulty syndrome
- Non-progressive cerebellar ataxia
- Progressive autosomal recessive cerebellar ataxia, sensorineural hearing loss syndrome
- Progressive truncal ataxia
- Recessive mitochondrial ataxia syndrome
- Richards-Rundle syndrome
- Sanger-Brown cerebellar ataxia
- Severe intellectual disability, agenesis of corpus callosum, facial dysmorphism, cerebellar ataxia syndrome
- Slurred speech
- Speech delay
- Spinocerebellar ataxia dysmorphism syndrome
- Spinocerebellar ataxia type 1
- Spinocerebellar ataxia type 10
- Spinocerebellar ataxia type 11
- Spinocerebellar ataxia type 12
- Spinocerebellar ataxia type 13
- Spinocerebellar ataxia type 14
- Spinocerebellar ataxia type 15/16
- Spinocerebellar ataxia type 17
- Spinocerebellar ataxia type 18
- Spinocerebellar ataxia type 19
- Spinocerebellar ataxia type 2
- Spinocerebellar ataxia type 20
- Spinocerebellar ataxia type 21
- Spinocerebellar ataxia type 23
- Spinocerebellar ataxia type 25
- Spinocerebellar ataxia type 26
- Spinocerebellar ataxia type 27
- Spinocerebellar ataxia type 28
- Spinocerebellar ataxia type 29
- Spinocerebellar ataxia type 30
- Spinocerebellar ataxia type 31
- Spinocerebellar ataxia type 32
- Spinocerebellar ataxia type 34
- Spinocerebellar ataxia type 35
- Spinocerebellar ataxia type 36
- Spinocerebellar ataxia type 37
- Spinocerebellar ataxia type 38
- Spinocerebellar ataxia type 4
- Spinocerebellar ataxia type 40
- Spinocerebellar ataxia type 41
- Spinocerebellar ataxia type 42
- Spinocerebellar ataxia type 43
- Spinocerebellar ataxia type 5
- Spinocerebellar ataxia type 6
- Spinocerebellar ataxia type 7
- Spinocerebellar ataxia type 8
- Spinocerebellar ataxia with axonal neuropathy type 1
- Third cranial nerve finding
- Truncal ataxia
- Unintelligible articulation
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G11.8: 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 G11.8, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming G11.8: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
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 G11.8 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G11.8Overview
What is the ICD-10 code for other hereditary ataxias?
The ICD-10-CM code for other hereditary ataxias is G11.8 (sometimes written as G118). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G11.8 (Hereditary ataxia) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other hereditary ataxias on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G11.8 group to?
When other hereditary ataxias 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 G11.8 a CC or MCC?
CMS lists G11.8 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.
What is the ICD-9 equivalent of G11.8?
Under the General Equivalence Mappings, other hereditary ataxias converts to ICD-9-CM 334.8 (spinocerebellar dis NEC). The mapping is approximate, so confirm the match fits the documentation.
What HCC is G11.8?
G11.8 (other hereditary ataxias) 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 G11.8 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G11.8 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.
