What is ICD-10 code G71.20?

G71.20 is the ICD-10-CM diagnosis code for Congenital myopathy, unspecified. A muscle weakness condition present from birth where the specific type cannot be determined or is not further specified. It belongs to the ICD-10-CM chapter for diseases of the nervous system (g00-g99). G71.20 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. G71.20 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. G71.20 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. G71.20 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for G71.20?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For G71.20, V28 maps to Muscular Dystrophy at RAF 0.426 while V24 mapped to Muscular Dystrophy at RAF 0.518. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting G71.20?

This is an unspecified code; use only when the specific type of congenital myopathy cannot be identified from documentation Encourage providers to specify the type (nemaline, centronuclear, etc.) for more precise coding Because G71.20 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM G71.20: Congenital myopathy

ICD-10-CM Code View

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Code lookupG71.20Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Diseases of myoneural junction and muscle (G70-G73)

G71.20

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Congenital myopathy, unspecified

A muscle weakness condition present from birth where the specific type cannot be determined or is not further specified.

Buddy Insight

Congenital myopathy, unspecified indicates a muscle disease present from birth that has not been further classified.

CMS-HCC V28

Mapped

HCC 197

Muscular Dystrophy

RAF 0.426

CMS-HCC V24

Mapped

HCC 76

Muscular Dystrophy

RAF 0.518

ACA/HHS

Mapped

HCC 117

HHS-HCC 117

Varies by metal level

ESRD/PACE

Mapped

HCC 76

Muscular Dystrophy

RAF 0.136

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

G71Primary disorders of muscles

G71.2Congenital myopathies

G71.20Congenital myopathy, unspecified

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for G71.20 in this effective period.

Excludes 2

Official

arthrogryposis multiplex congenita (Q74.3)

Related Child Codes

Official

G71.21Nemaline myopathy

G71.22Centronuclear myopathy

G71.29Other congenital myopathy

Includes

Official

ICD-10-CM does not list Includes notes for G71.20 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for G71.20 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for G71.20 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for G71.20 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for G71.20 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Congenital onset of muscle weakness: present from birth or early infancy

Clinical features: hypotonia, delayed motor milestones, proximal or generalized weakness

Diagnostic workup status: muscle biopsy, genetic testing (pending or inconclusive)

Documentation of why specific type cannot be determined

MEAT Support

HCC Buddy guidance

Congenital onset of muscle weakness: present from birth or early infancy

Clinical features: hypotonia, delayed motor milestones, proximal or generalized weakness

Diagnostic workup status: muscle biopsy, genetic testing (pending or inconclusive)

Documentation of why specific type cannot be determined

Audit Caution

HCC Buddy guidance

Using this code when muscle biopsy or genetic testing has identified a specific congenital myopathy type

Confusing congenital myopathy with muscular dystrophy — myopathies are often non-progressive while dystrophies are progressive

Coding as congenital hypotonia (symptom) instead of the underlying congenital myopathy diagnosis

Not updating the code when additional diagnostic information becomes available

Common Mistakes

HCC Buddy guidance

G71.21 — Nemaline myopathy should be used when characteristic nemaline rods are identified on biopsy

G71.220 — X-linked myotubular myopathy should be used when this specific genetic form is confirmed

G71.00 — Muscular dystrophy, unspecified involves progressive muscle destruction, while congenital myopathies are typically static or slowly progressive

P94.2 — Congenital hypotonia is a symptom code, not a diagnosis code for congenital myopathy

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is G71.20 an HCC code?

Yes. G71.20 (Congenital myopathy, unspecified) maps to Muscular Dystrophy under the CMS-HCC V28 risk adjustment model (and Muscular Dystrophy under V24), with a community non-dual aged RAF of 0.426. It is billable for payment year 2026.

Coder answer: G71.20 is billable and maps to V28 HCC 197, Muscular Dystrophy. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: G71.20
Description: Congenital myopathy, unspecified
HCC (V28): HCC 197 — Muscular Dystrophy
RAF: 0.426
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 197, Muscular Dystrophy

0.426

V24HCC 76, Muscular Dystrophy

0.518

ESRDHCC 76, Muscular Dystrophy

0.136

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.

Work G71.20 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for G71.20

For G71.20 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 G71.20 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

G71.20 is the ICD-10-CM diagnosis code for congenital myopathy, unspecified. A muscle weakness condition present from birth where the specific type cannot be determined or is not further specified. G71.20 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, G71.20 maps to Muscular Dystrophy (HCC 197) with a community, non-dual, aged base RAF weight of 0.426. Under the older V24 model, G71.20 mapped to the same category but with a base RAF weight of 0.518, 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.

This is an unspecified code; use only when the specific type of congenital myopathy cannot be identified from documentation. Because G71.20 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 G71.20 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is an unspecified code; use only when the specific type of congenital myopathy cannot be identified from documentation
•Encourage providers to specify the type (nemaline, centronuclear, etc.) for more precise coding

Clinical Significance

Congenital myopathy, unspecified indicates a muscle disease present from birth that has not been further classified. These conditions cause significant lifelong disability including weakness, hypotonia, and potential respiratory compromise. While unspecified, this code captures the chronic progressive nature of the condition for risk adjustment and signals the need for multidisciplinary pediatric or adult neuromuscular care.

Documentation Requirements

✓Congenital onset of muscle weakness: present from birth or early infancy
✓Clinical features: hypotonia, delayed motor milestones, proximal or generalized weakness
✓Diagnostic workup status: muscle biopsy, genetic testing (pending or inconclusive)
✓Documentation of why specific type cannot be determined
✓Functional status and respiratory function
✓Provider's explicit diagnosis of congenital myopathy

Commonly Confused Codes

•G71.21: Nemaline myopathy should be used when characteristic nemaline rods are identified on biopsy
•G71.220: X-linked myotubular myopathy should be used when this specific genetic form is confirmed
•G71.00: Muscular dystrophy, unspecified involves progressive muscle destruction, while congenital myopathies are typically static or slowly progressive
•P94.2: Congenital hypotonia is a symptom code, not a diagnosis code for congenital myopathy