E74.05
BillableLysosome-associated membrane protein 2 [LAMP2] deficiency
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E74.05 an HCC code?
Yes. E74.05 maps to Amyloidosis, Porphyria, and Other Specified Metabolic Disorders under the CMS-HCC V28 risk adjustment model (and Other Significant Endocrine and Metabolic Disorders 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 E74.05
For E74.05to 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 E74.05 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E74.05 is the ICD-10-CM diagnosis code for lysosome-associated membrane protein 2 [lamp2] deficiency. A rare inherited disorder caused by deficiency of a protein called LAMP2, leading to glycogen accumulation in muscles and the heart, causing weakness and heart problems. E74.05 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 CMS-HCC V28 risk adjustment model, E74.05 maps to Amyloidosis, Porphyria, and Other Specified Metabolic Disorders (HCC 50) with a community, non-dual, aged base RAF weight of 0.648. Under the older CMS-HCC V24 model, E74.05 maps to Other Significant Endocrine and Metabolic Disorders (HCC 23) with a community, non-dual, aged base RAF weight of 0.194. 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.
Also known as Danon disease; document cardiac involvement including cardiomyopathy and arrhythmias. Because E74.05 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 E74.05 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Also known as Danon disease; document cardiac involvement including cardiomyopathy and arrhythmias
- •Note that this condition often presents with muscle weakness and cardiac symptoms; genetic testing confirmation should be documented
Clinical Significance
LAMP2 deficiency (Danon disease) is an X-linked lysosomal storage disorder caused by mutations in the LAMP2 gene, leading to glycogen accumulation in cardiac and skeletal muscle. Males typically develop severe hypertrophic cardiomyopathy, often requiring heart transplantation, while females have a later, milder presentation. This is a life-threatening condition that carries significant cardiac mortality risk.
Documentation Requirements
- ✓Confirmed diagnosis of LAMP2 deficiency or Danon disease
- ✓Genetic testing confirming LAMP2 gene mutation
- ✓Cardiac evaluation including echocardiogram showing hypertrophic cardiomyopathy
- ✓Electrocardiogram findings including Wolff-Parkinson-White pattern if present
- ✓Muscle involvement assessment including creatine kinase levels
- ✓Family history and inheritance pattern documentation
Code Also
Commonly Confused Codes
- •E74.02 — Pompe disease: also causes cardiac and muscle glycogen accumulation but involves acid maltase deficiency
- •I42.1 — Obstructive hypertrophic cardiomyopathy: the cardiomyopathy is a manifestation of Danon disease
- •I42.2 — Other hypertrophic cardiomyopathy: code the underlying Danon disease as primary
- •E74.00 — Glycogen storage disease, unspecified: do not use when LAMP2 deficiency is confirmed
- •E74.09 — Other glycogen storage disease: LAMP2 deficiency now has its own specific code