What is ICD-10 code E75.09?

E75.09 is the ICD-10-CM diagnosis code for Other GM2 gangliosidosis. A rare inherited metabolic disorder where harmful fatty substances (GM2 gangliosides) accumulate in nerve and brain cells, causing progressive neurological damage, with a variant type not otherwise specified. E75.09 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E75.09 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. E75.09 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. E75.09 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.

Which HCC does E75.09 map to under V28?

E75.09 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

What does E75.09 pay in RAF?

E75.09 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

What is the V28 vs V24 difference for E75.09?

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. E75.09 was a payment HCC under V24 (Dementia Without Complication) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What documentation supports E75.09?

Confirm the specific GM2 gangliosidosis variant (Tay-Sachs, Sandhoff, etc.) is documented; if specified, use the appropriate code instead Ensure genetic testing results are referenced in the medical record to support diagnosis Because E75.09 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. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM E75.09: Other GM2 gangliosidosis

E75.09 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · HCC coding software

ICD-10-CM Code View

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Code lookupE75.09Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Metabolic disorders (E70-E88)

E75.09

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

Other GM2 gangliosidosis

A rare inherited metabolic disorder where harmful fatty substances (GM2 gangliosides) accumulate in nerve and brain cells, causing progressive neurological damage, with a variant type not otherwise specified.

Buddy Insight

Other GM2 gangliosidosis captures rare variants of GM2 ganglioside accumulation disorders not classified as Tay-Sachs or Sandhoff, primarily the GM2 activator protein deficiency (AB variant).

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Mapped

HCC 52

Dementia Without Complication

RAF 0.346

ACA/HHS

Mapped

HCC 119

HHS-HCC 119

Varies by metal level

ESRD/PACE

Mapped

HCC 52

Dementia Without Complication

RAF 0.042

RXHCC

Mapped

HCC 41

Lysosomal Storage Disorders

RAF 3.081

Code Book Path

Official

E75Disorders of sphingolipid metabolism and other lipid storage disorders

E75.0GM2 gangliosidosis

E75.09Other GM2 gangliosidosis

Inclusion Terms

Official

Adult GM2 gangliosidosis
Juvenile GM2 gangliosidosis

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E75.09 in this effective period.

Related Child Codes

Official

E75.00GM2 gangliosidosis, unspecified

E75.01Sandhoff disease

E75.02Tay-Sachs disease

Includes

Official

ICD-10-CM does not list Includes notes for E75.09 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for E75.09 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E75.09 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E75.09 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E75.09 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documented diagnosis of GM2 gangliosidosis specifying a variant other than Tay-Sachs or Sandhoff

Specialized testing: GM2 activator protein assay or GM2A gene mutation analysis

Normal hexosaminidase A and B levels with GM2 ganglioside accumulation on tissue analysis

Neurological assessment and disease progression documentation

MEAT Support

HCC Buddy guidance

Documented diagnosis of GM2 gangliosidosis specifying a variant other than Tay-Sachs or Sandhoff

Specialized testing: GM2 activator protein assay or GM2A gene mutation analysis

Normal hexosaminidase A and B levels with GM2 ganglioside accumulation on tissue analysis

Neurological assessment and disease progression documentation

Audit Caution

HCC Buddy guidance

Misdiagnosing GM2 activator deficiency as Tay-Sachs because the clinical presentation is identical

Using the unspecified GM2 code when the activator protein deficiency has been confirmed

Not recognizing that normal hexosaminidase levels do not rule out GM2 gangliosidosis (AB variant)

Failing to document the specific variant for accurate coding and genetic counseling

Common Mistakes

HCC Buddy guidance

E75.02 — Tay-Sachs disease: clinically identical but has hexosaminidase A deficiency

E75.01 — Sandhoff disease: different enzyme profile (hex A and B deficient)

E75.00 — GM2 gangliosidosis, unspecified: use only when specific variant cannot be determined

E75.19 — Other gangliosidosis: for non-GM2 gangliosidoses

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 E75.09 an HCC code?

Yes. E75.09 maps to Dementia Without Complication under the V24 model but is not retained in V28.

Code: E75.09
Description: Other GM2 gangliosidosis
HCC (V28): No CMS-HCC V28 mapping
RAF: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

V24HCC 52, Dementia Without Complication

0.346

ESRDHCC 52, Dementia Without Complication

0.042

RxHCCHCC 41, Lysosomal Storage Disorders

3.081

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 E75.09 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E75.09

For E75.09 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 E75.09 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E75.09 is the ICD-10-CM diagnosis code for other gm2 gangliosidosis. A rare inherited metabolic disorder where harmful fatty substances (GM2 gangliosides) accumulate in nerve and brain cells, causing progressive neurological damage, with a variant type not otherwise specified. E75.09 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering metabolic disorders (e70-e88).

Under the older CMS-HCC V24 model, E75.09 maps to Dementia Without Complication (HCC 52) with a community, non-dual, aged base RAF weight of 0.346. 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.

Confirm the specific GM2 gangliosidosis variant (Tay-Sachs, Sandhoff, etc.) is documented; if specified, use the appropriate code instead. Because E75.09 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 E75.09 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm the specific GM2 gangliosidosis variant (Tay-Sachs, Sandhoff, etc.) is documented; if specified, use the appropriate code instead
•Ensure genetic testing results are referenced in the medical record to support diagnosis

Clinical Significance

Other GM2 gangliosidosis captures rare variants of GM2 ganglioside accumulation disorders not classified as Tay-Sachs or Sandhoff, primarily the GM2 activator protein deficiency (AB variant). This ultra-rare condition produces a clinical picture identical to Tay-Sachs but with normal hexosaminidase enzyme levels, making diagnosis challenging. The distinction requires specialized biochemical or genetic testing.

Documentation Requirements

✓Documented diagnosis of GM2 gangliosidosis specifying a variant other than Tay-Sachs or Sandhoff
✓Specialized testing: GM2 activator protein assay or GM2A gene mutation analysis
✓Normal hexosaminidase A and B levels with GM2 ganglioside accumulation on tissue analysis
✓Neurological assessment and disease progression documentation
✓Genetic counseling and family screening status

Commonly Confused Codes

•E75.02: Tay-Sachs disease: clinically identical but has hexosaminidase A deficiency
•E75.01: Sandhoff disease: different enzyme profile (hex A and B deficient)
•E75.00: GM2 gangliosidosis, unspecified: use only when specific variant cannot be determined
•E75.19: Other gangliosidosis: for non-GM2 gangliosidoses
•E75.10: Unspecified gangliosidosis: too non-specific