2027 ICD-10-CM Diagnosis Code G40.C09Lafora progressive myoclonus epilepsy, not intractable, without status epilepticus
ICD-10-CM Codes›G00–G99›G40-G47›G40
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 201
- Chronic Condition
G40.C09 is a billable ICD-10-CM diagnosis code for lafora progressive myoclonus epilepsy, not intractable, without status epilepticus. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 23, 100 through 101. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 89 closely related codes. Coders also document this condition as lafora disease. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Epilepsy; convulsions.
For Medicare Advantage risk adjustment, G40.C09 maps to CMS-HCC Category 201 (Seizure Disorders and Convulsions) under the V28 model, adding a risk factor of about 0.245 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
G40.C09 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Lafora disease
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G40.C09: its own notes plus those printed at G40.C, G40, and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Lafora progressive myoclonus epilepsy NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Code Also
A second code may be needed to fully describe the condition; the note gives no sequencing direction.
Notes
General instructions on how these codes are used.
- the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G40.C09, its category, or a range that includes it.
Excludes1 3
These codes carry an Excludes1 note naming G40.C09: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 2
These codes carry an Excludes2 note naming G40.C09: its condition is not part of those codes, and both may be reported when the patient has both.
Code First 1
These codes say to code first a condition named in the note, and G40.C09 is one of the conditions named.
Use Additional Code 2
These codes say to use an additional code from the note, and G40.C09 is one of the codes named.
Code Also 10
These codes say G40.C09 may also be needed to fully describe the condition. The note gives no sequencing direction.
- E20.810 Autosomal dominant hypocalcemiaseizure disorder (G40.-, R56.9) names G40.-, which includes this code
- F78.A1 SYNGAP1-related intellectual disabilityepilepsy and recurrent seizures (G40.-) names G40.-, which includes this code
- G04.8 Other encephalitis, myelitis and encephalomyelitisany associated seizure (G40.-, R56.9) names G40.-, which includes this code
- G40.5 Epileptic seizures related to external causesif applicable, associated epilepsy and recurrent seizures (G40.-) names G40.-, which includes this code
- G43.1 Migraine with auraany associated seizure (G40.-, R56.9) names G40.-, which includes this code
- G93.45 Developmental and epileptic encephalopathyepilepsy, by specific type (G40.-) names G40.-, which includes this code
- I67.850 Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathyepilepsy (G40.-) names G40.-, which includes this code
- Q87.85 MED13L syndromeepilepsy and recurrent seizures (G40.-) names G40.-, which includes this code
- QA0 Neurodevelopmental disorders related to specific genetic pathogenic variantsepilepsy, by specific type (G40.-) names G40.-, which includes this code
- Z15.1 Genetic susceptibility to epilepsy and neurodevelopmental disordersepilepsy, by specific type (G40.-) names G40.-, which includes this code
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
Lafora body See Also: Epilepsy, progressive, Lafora; G40.C09
Epilepsy, epileptic, epilepsia (attack) (cerebral) (convulsion) (fit) (seizure) G40.909
Lafora progressive myoclonus See Also: Epilepsy, myoclonus, progressive, Lafora; G40.C09
myoclonus, myoclonic See Also: Epilepsy, generalized, specified NEC;
progressive See Also: Epilepsy, generalized, idiopathic;
Lafora G40.C09
not intractable G40.C09
without status epilepticus G40.C09
progressive (familial) myoclonic See: Epilepsy, myoclonus, progressive;
Lafora See Also: Epilepsy, myoclonus, progressive, Lafora; G40.C09
Lafora disease See Also: Epilepsy, progressive, Lafora; G40.C09
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Lafora Disease
a form of stimulus sensitive myoclonic epilepsy inherited as an autosomal recessive condition. the most common presenting feature is a single seizure in the second decade of life. this is followed by progressive myoclonus, myoclonic seizures, tonic-clonic seizures, focal occipital seizures, intellectual decline, and severe motor and coordination impairments. most affected individuals do not live past the age of 25 years. concentric amyloid (lafora) bodies are found in neurons, liver, skin, bone, and muscle (from menkes, textbook of childhood neurology, 5th ed, pp111-110).
Patient EducationClinical
Epilepsy
Epilepsy is a brain disorder that causes people to have recurring seizures. The seizures happen when clusters of nerve cells, or neurons, in the brain send out the wrong signals. People may have strange sensations and emotions or behave strangely. They may have violent muscle spasms or lose consciousness.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Code History & ChangesHistory
Replacement G40.C09 replaces the following previously assigned code(s):
- G40.309 - Gen idiopathic epilepsy, not intractable, w/o stat epi
Questions About G40.C09Overview
Is G40.C09 (Lafora progressive myoclonus epilepsy, not intractable) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report lafora progressive myoclonus epilepsy, not intractable, without status epilepticus on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G40.C09 group to?
When lafora progressive myoclonus epilepsy, not intractable, without status epilepticus is the principal diagnosis on an inpatient stay, it groups to MS-DRG 100, 23, 101, with relative weights from 0.8952 to 5.7422 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G40.C09 a CC or MCC?
CMS lists G40.C09 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 89 closely related codes in its exclusion list.
Can G40.C09 be reported with F44.5?
Not as a rule. The Excludes1 note at G40, which applies to G40.C09, lists "conversion disorder with seizures (F44.5)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is G40.C09?
G40.C09 (lafora progressive myoclonus epilepsy, not intractable, without status epilepticus) maps to CMS-HCC Category 201 (Seizure Disorders and Convulsions), commonly written as HCC 201, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 79 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 164.
Does G40.C09 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G40.C09 adds a risk adjustment factor of about 0.245 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.131 to 0.245 depending on the payment segment). HCC 201 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 201 category page.
