G40.841
BillableKCNQ2-related epilepsy, not intractable, with status epilepticus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G40.841 an HCC code?
Yes. G40.841 maps to Seizure Disorders and Convulsions under the CMS-HCC V28 risk adjustment model (and Seizure Disorders and Convulsions 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 G40.841
For G40.841to 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 G40.841 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G40.841 is the ICD-10-CM diagnosis code for kcnq2-related epilepsy, not intractable, with status epilepticus. Epilepsy caused by a KCNQ2 gene mutation that can be controlled with medication, currently experiencing a prolonged seizure state. G40.841 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).
Under the CMS-HCC V28 risk adjustment model, G40.841 maps to Seizure Disorders and Convulsions (HCC 201) with a community, non-dual, aged base RAF weight of 0.262. Under the older V24 model, G40.841 mapped to the same category but with a base RAF weight of 0.244 — 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 genetic testing confirming KCNQ2 mutation is documented. Because G40.841 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 G40.841 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify genetic testing confirming KCNQ2 mutation is documented
- •Confirm status epilepticus is present and that seizures are responsive to medication
Clinical Significance
KCNQ2-related epilepsy with status epilepticus identifies a genetic epilepsy caused by mutations in the KCNQ2 potassium channel gene. Neonatal-onset seizures are typical, and some forms respond well to sodium channel blockers. Status epilepticus in this condition requires emergency management while considering the specific pharmacological sensitivities of KCNQ2-related seizures.
Documentation Requirements
- ✓Genetic testing confirming KCNQ2 mutation
- ✓Documentation of active status epilepticus during encounter
- ✓Statement that seizures respond to medication (not intractable)
- ✓Neonatal or early-onset seizure history
- ✓Current medication regimen (sodium channel blockers may be particularly effective)
- ✓Emergency interventions for status epilepticus
Commonly Confused Codes
- •G40.842 — KCNQ2 epilepsy, not intractable, WITHOUT status epilepticus
- •G40.843 — KCNQ2 epilepsy, INTRACTABLE, with status epilepticus
- •G40.42 — CDKL5 Deficiency; different genetic epilepsy
- •G40.401 — Other generalized epilepsy with status epilepticus; use when KCNQ2 is not confirmed
- •P90 — Convulsions of newborn; acute neonatal seizures without established genetic diagnosis