ICD-10 Code G40.843 – KCNQ2-related epilepsy, intractable, with status epilepticus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G40.843 – KCNQ2-related epilepsy, intractable, with status epilepticus
What it is
This code identifies a genetic epilepsy linked to KCNQ2 that does not respond well to treatment and includes status epilepticus. Use it when documentation clearly states this specific diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Commonly, patients have recurrent seizures, poor seizure control despite therapy, and a prolonged seizure episode consistent with status epilepticus.
When to use this code
Use G40.843 when the provider documents KCNQ2-related epilepsy, intractable, with status epilepticus. It is appropriate for encounters focused on ongoing seizure disorder management or evaluation after a prolonged seizure episode. If the record does not specify intractable disease or status epilepticus, check documentation.
Do not use for
Do not use this code for epilepsy without KCNQ2 involvement, or when intractable status is not documented. Check documentation if the seizure type or genetic cause is unclear.
Coding tip
Verify all three elements—KCNQ2-related, intractable, and status epilepticus—before assigning G40.843.