ICD-10-CM 2027
ICD-10 code for cerebellar hereditary ataxia
From the official ICD-10-CM alphabetic index entry “Ataxia, ataxy, ataxic › cerebellar (hereditary)”. Page updated September 29, 2026.
About coding cerebellar hereditary ataxia
The ICD-10-CM code for cerebellar hereditary ataxia is G11.9 (Hereditary ataxia, unspecified). The official index lists 11 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on G11.9.
Within G11, choose G11.9 (unspecified) only when documentation doesn't support a more specific option: congenital nonprogressive ataxia (G11.0), early-onset cerebellar ataxia (G11.1), Late-onset cerebellar ataxia (G11.2), cerebellar ataxia with defective DNA repair (G11.3), hereditary spastic paraplegia (G11.4), Hypomyelination - hypogonadotropic hypogonadism - hypodontia (G11.5), leukodystrophy with vanishing white matter disease (G11.6) and other hereditary ataxias (G11.8).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 058 (Multiple Sclerosis and Cerebellar Ataxia with MCC, relative weight 1.8438), DRG 059 (Multiple Sclerosis and Cerebellar Ataxia with CC, relative weight 1.2002) and DRG 060 (Multiple Sclerosis and Cerebellar Ataxia without CC/MCC, relative weight 0.9247), in MDC 01 (Diseases and Disorders of the Nervous System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific cerebellar hereditary ataxia codes (official index)
- with defective DNA repair G11.3 — Cerebellar ataxia with defective DNA repair
- alcoholic G31.2 — Degeneration of nervous system due to alcohol
- early-onset G11.10 — Early-onset cerebellar ataxia, unspecified
- with
- essential tremor G11.19 — Other early-onset cerebellar ataxia
- myoclonus [Hunt's ataxia] G11.19 — Other early-onset cerebellar ataxia
- retained tendon reflexes G11.19 — Other early-onset cerebellar ataxia
- in
- alcoholism G31.2 — Degeneration of nervous system due to alcohol
- myxedema E03.9 — Hypothyroidism, unspecified
- neoplastic disease D49.9 — Neoplasm of unspecified behavior of unspecified site
- specified disease NEC G32.81 — Cerebellar ataxia in diseases classified elsewhere
- late-onset (Marie's) G11.2 — Late-onset cerebellar ataxia
Common questions about cerebellar hereditary ataxia ICD-10 codes
What is the ICD-10 code for cerebellar hereditary ataxia?
- G11.9 — Hereditary ataxia, unspecified. More specific codes apply when the documentation supports them: G11.3, G31.2, G11.10, G11.19 and others below.
What is the ICD-10 code for alcoholic cerebellar hereditary ataxia?
- G31.2 — Degeneration of nervous system due to alcohol.
What is the ICD-10 code for early-onset cerebellar hereditary ataxia?
- G11.10 — Early-onset cerebellar ataxia, unspecified.
What is the ICD-10 code for late-onset cerebellar hereditary ataxia?
- G11.2 — Late-onset cerebellar ataxia.
Is G11.9 billable?
- Yes. G11.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G11.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G11.9 as a principal diagnosis.
Is G11.9 a CC or MCC?
- G11.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.