E76.22
BillableSanfilippo mucopolysaccharidoses
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E76.22 an HCC code?
Yes. E76.22 maps to Lysosomal Storage 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 E76.22
For E76.22 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 E76.22 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E76.22 is the ICD-10-CM diagnosis code for sanfilippo mucopolysaccharidoses. Sanfilippo mucopolysaccharidosis is a rare inherited metabolic disorder characterized by severe neurological deterioration, behavioral problems, and progressive dementia in childhood. E76.22 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, E76.22 maps to Lysosomal Storage Disorders (HCC 49) with a community, non-dual, aged base RAF weight of 0.226. Under the older CMS-HCC V24 model, E76.22 maps to Other Significant Endocrine and Metabolic Disorders (HCC 23) with a community, non-dual, aged base RAF weight of 0.230. 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.
Sanfilippo syndrome has four subtypes (A, B, C, D) based on different enzyme deficiencies; document the specific type if known. Because E76.22 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 E76.22 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Sanfilippo syndrome has four subtypes (A, B, C, D) based on different enzyme deficiencies; document the specific type if known
- •Document neuropsychiatric symptoms, developmental regression, and behavioral changes as these are hallmark features
Clinical Significance
Sanfilippo mucopolysaccharidosis (MPS III) is characterized by severe progressive neurodegeneration with relatively mild somatic features, making it distinct from other MPS types. The four subtypes (A-D) involve different enzyme deficiencies but share a clinical picture of behavioral disturbances, sleep disorders, cognitive decline, and shortened lifespan, with onset typically in early childhood.
Documentation Requirements
- ✓Specific diagnosis of Sanfilippo syndrome or MPS III documented
- ✓Subtype if known (A, B, C, or D) though all map to the same code
- ✓Confirmatory enzyme assay or genetic testing results
- ✓Neurological and behavioral assessment: hyperactivity, aggression, sleep disturbance, cognitive regression
- ✓Current functional status and care needs
- ✓Treatment plan including behavioral management, seizure control, and supportive care