G12.0
BillableInfantile spinal muscular atrophy, type I [Werdnig-Hoffman]
HCC Category Mapping
V28HCC 190 — Motor Neuron Disease, Including Amyotrophic Lateral Sclerosis
0.935V24HCC 72 — Spinal Cord Disorders/Injuries
0.464ESRDHCC 72 — Spinal Cord Disorders/Injuries
0.000RxHCCHCC 155 — Myelitis and Encephalomyelitis
0.000What This Code Means
A severe inherited muscle-wasting disease that appears in infancy, characterized by progressive weakness and muscle loss, also known as Werdnig-Hoffman disease.
Coding Tips
- •This is a specific diagnosis code; ensure documentation confirms infantile onset and type I classification before coding
- •This condition typically has early mortality; coordinate with palliative care documentation if applicable
Clinical Significance
Infantile spinal muscular atrophy type I (Werdnig-Hoffman disease) is the most severe form of spinal muscular atrophy, typically presenting before 6 months of age with profound hypotonia and progressive weakness. Without treatment, life expectancy is under 2 years. With new gene therapy (Zolgensma) and antisense oligonucleotide (Spinraza) treatments, this diagnosis drives extremely high pharmaceutical and care costs.
Documentation Requirements
- ✓Confirmed diagnosis via SMN1 gene deletion testing
- ✓Age of onset before 6 months
- ✓Profound hypotonia and inability to sit unsupported
- ✓Classification as type I (most severe infantile form)
- ✓Current ventilatory and nutritional support status
- ✓Treatment with disease-modifying therapy if applicable (nusinersen, onasemnogene abeparvovec, risdiplam)
Commonly Confused Codes
G12.1 — Other inherited spinal muscular atrophy: for types II, III, and IV which have later onset and milder courseG12.9 — Spinal muscular atrophy, unspecified: should not be used when type I is confirmedG71.0 — Muscular dystrophy: different genetic mechanism causing muscle weaknessG12.8 — Other spinal muscular atrophies: for atypical or non-inherited forms
Code Hierarchy
└G12Spinal muscular atrophy and related syndromes└G12.0Infantile spinal muscular atrophy, type I [Werdnig-Hoffman]
└G12.0Infantile spinal muscular atrophy, type I [Werdnig-Hoffman]