2026 ICD-10-CM Diagnosis Code G40.842KCNQ2-related epilepsy, not intractable, without status epilepticus

ICD-10-CM Codes›G00–G99›G40-G47›G40

ICD-10-CM G40.842
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G40.842 is a billable ICD-10-CM diagnosis code for KCNQ2-related epilepsy, not intractable, without status epilepticus. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 100 through 101. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Epilepsy; convulsions.

Code Identity

ICD-10-CM Code
G40.842
Billable Status
Yes — Valid for Submission
Code Describes
KCNQ2-related epilepsy, not intractable, without status epilepticus
Short Description
KCNQ2-related epilepsy, not intractable, without stat epi
Parent Code
G40.84
KCNQ2-related epilepsy

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG40Epilepsy and recurrent seizures
This CodeG40.842KCNQ2-related epilepsy, not intractable, without status epilepticus

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • KCNQ2-related epilepsy NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • KCNQ2-related
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • KCNQ2-related
        • not intractable
    • Epilepsy, epileptic, epilepsia(attack) (cerebral) (convulsion) (fit) (seizure)
      • KCNQ2-related
        • not intractable
          • without status epilepticus

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS009
Epilepsy; convulsions
Default principal diagnosis: inpatient Yes · outpatient Yes

Code History & ChangesHistory

Replacement G40.842 replaces the following previously assigned code(s):

  • G40.89 - Other seizures
FY 2025AddedAdded to the ICD-10-CM code setEffective October 1, 2024.
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About G40.842Overview

Is G40.842 (KCNQ2-related epilepsy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report KCNQ2-related epilepsy, not intractable, without status epilepticus on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does G40.842 group to?

When KCNQ2-related epilepsy, not intractable, without status epilepticus is the principal diagnosis on an inpatient stay, it groups to MS-DRG 100, 101, with relative weights from 0.9026 to 1.9368 depending on complications. Higher weights mean higher Medicare reimbursement.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.