ICD-10-CM 2027 diagnosis code
G12.0Infantile spinal muscular atrophy, type I [Werdnig-Hoffman]
G12.0 is a valid, billable ICD-10-CM code for infantile spinal muscular atrophy, type i [werdnig-hoffman]. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Werdnig-Hoffmann syndrome.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About G12.0
G12.0 is the ICD-10-CM diagnosis code for infantile spinal muscular atrophy, type I [Werdnig-Hoffman]. It belongs to category G12 (spinal muscular atrophy and related syndromes), block G10-G14 (systemic atrophies primarily affecting the central nervous system) and chapter 6 (diseases of the nervous system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within G12 (spinal muscular atrophy and related syndromes), G12.0 is specifically for infantile spinal muscular atrophy, type I [Werdnig-Hoffman]. Related codes cover other inherited spinal muscular atrophy (G12.1), motor neuron disease (G12.2), other spinal muscular atrophies and related syndromes (G12.8) and spinal muscular atrophy, unspecified (G12.9).
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 056 (Degenerative Nervous System Disorders with MCC, relative weight 2.2655) and DRG 057 (Degenerative Nervous System Disorders without MCC, relative weight 1.2838), 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.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 335.0 (Werdnig-Hoffmann disease).
Notes that apply from higher levels
Instructions written at a parent level also apply to G12.0.
Broader instructions also apply from Chapter 6: Diseases of the nervous system.
Alphabetic index entries
9 entriesTerms in the official ICD-10-CM index that lead to G12.0.
- Atrophy, atrophic (of) › muscle, muscular (diffuse) (general) (idiopathic) (primary) › infantile spinal
- Atrophy, atrophic (of) › muscle, muscular (diffuse) (general) (idiopathic) (primary) › progressive (bulbar) › infantile (spinal)
- Atrophy, atrophic (of) › muscle, muscular (diffuse) (general) (idiopathic) (primary) › progressive (bulbar) › spinal › infantile
- Atrophy, atrophic (of) › muscle, muscular (diffuse) (general) (idiopathic) (primary) › spinal › infantile, type I (Werdnig-Hoffmann)
- Atrophy, atrophic (of) › Werdnig-Hoffmann
- Disease, diseased › Werdnig-Hoffmann
- Syndrome › Hoffmann-Werdnig
- Syndrome › Werdnig-Hoffman
- Werdnig-Hoffmann syndrome (muscular atrophy)
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 01 · Diseases and Disorders of the Nervous System
ICD-9-CM equivalent
Converter →- 335.0Werdnig-Hoffmann diseaseexact
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about G12.0
Is G12.0 billable?
- Yes. G12.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G12.0 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G12.0 as a principal diagnosis.
Is G12.0 a CC or MCC?
- G12.0 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.
What DRG does G12.0 group to?
- G12.0 is used in the MS-DRG v44.0 logic for MS-DRG 056 (Degenerative Nervous System Disorders with MCC) and MS-DRG 057 (Degenerative Nervous System Disorders without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for G12.0?
- The CMS General Equivalence Mappings map G12.0 to ICD-9-CM 335.0.