G71.11
BillableMyotonic muscular dystrophy
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G71.11 an HCC code?
Yes. G71.11 maps to Muscular Dystrophy under the CMS-HCC V28 risk adjustment model (and Muscular Dystrophy under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for G71.11
For G71.11 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- 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
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed G71.11 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G71.11 is the ICD-10-CM diagnosis code for myotonic muscular dystrophy. Myotonic muscular dystrophy is a genetic muscle disease where muscles become weak and stiff, and have difficulty relaxing after contraction. Patients experience progressive muscle weakness and may have other complications affecting the heart, eyes, and endocrine system. G71.11 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering diseases of myoneural junction and muscle (g70-g73).
Under the CMS-HCC V28 risk adjustment model, G71.11 maps to Muscular Dystrophy (HCC 197) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, G71.11 mapped to the same category but with a base RAF weight of 0.358 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Verify the specific type of myotonic dystrophy (type 1 vs type 2) in the medical record, as G71.11 specifically indicates type 1; type 2 would be coded differently. Because G71.11 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, and MEAT documentation criteria for G71.11 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify the specific type of myotonic dystrophy (type 1 vs type 2) in the medical record, as G71.11 specifically indicates type 1; type 2 would be coded differently
- •Look for associated manifestations such as cardiac arrhythmias, cataracts, or endocrine disorders that should be coded separately to capture the full clinical picture
Clinical Significance
Myotonic muscular dystrophy (Steinert disease/DM1) is a multisystem disorder with unique features including myotonia (delayed muscle relaxation), progressive weakness, and involvement of cardiac, endocrine, ocular, and central nervous systems. It is the most common adult-onset muscular dystrophy. Accurate coding captures the systemic nature and complexity of care required for these patients.
Documentation Requirements
- ✓Genetic testing confirming CTG trinucleotide repeat expansion in DMPK gene
- ✓Clinical features: myotonia, progressive distal-predominant weakness, facial weakness
- ✓Multisystem assessment: cardiac (conduction defects, cardiomyopathy), endocrine (diabetes, thyroid), ocular (cataracts)
- ✓Severity assessment and disease progression
- ✓Current treatment: symptom management, cardiac monitoring protocol
- ✓Provider's explicit diagnosis of myotonic muscular dystrophy
Commonly Confused Codes
- •G71.12 — Myotonia congenita involves myotonia without progressive weakness or multisystem involvement
- •G71.00 — Muscular dystrophy, unspecified should not be used when myotonic type is documented
- •G71.01 — Duchenne or Becker muscular dystrophy does not feature myotonia
- •G71.19 — Other specified myotonic disorders is for non-dystrophic myotonic conditions