What is ICD-10 code E75.27?

E75.27 is the ICD-10-CM diagnosis code for Pelizaeus-Merzbacher disease. A rare inherited neurological disorder affecting the development and maintenance of myelin (the protective coating around nerve fibers), causing progressive weakness and loss of motor control. E75.27 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E75.27 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. E75.27 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. E75.27 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for E75.27?

E75.27 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards E75.27 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

What should coders know when reporting E75.27?

Document the specific type: classic, connatal, or transitional form to support medical necessity Link to associated neurological complications such as spasticity or developmental delays

E75.27: Pelizaeus-Merzbacher disease — ICD-10

ICD-10-CM Code View

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Code lookupE75.27Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Metabolic disorders (E70-E88)

E75.27

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Pelizaeus-Merzbacher disease

A rare inherited neurological disorder affecting the development and maintenance of myelin (the protective coating around nerve fibers), causing progressive weakness and loss of motor control.

Buddy Insight

Pelizaeus-Merzbacher disease is an X-linked hypomyelinating disorder caused by PLP1 gene mutations affecting proteolipid protein production, which is essential for myelin formation.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Not risk-adjusted for this model/period.

RAF 0

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Not risk-adjusted for this model/period.

RAF 0

RXHCC

Mapped

HCC 41

Lysosomal Storage Disorders

RAF 0.0

Code Trumping

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Code Book Path

Official

E75Disorders of sphingolipid metabolism and other lipid storage disorders

E75.2Other sphingolipidosis

E75.27Pelizaeus-Merzbacher disease

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for E75.27 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E75.27 in this effective period.

Related Child Codes

Official

E75.21Fabry (-Anderson) disease

E75.22Gaucher disease

E75.23Krabbe disease

E75.24Niemann-Pick disease

E75.25Metachromatic leukodystrophy

Includes

Official

ICD-10-CM does not list Includes notes for E75.27 in this effective period.

Excludes 1

Official

adrenoleukodystrophy [Addison-Schilder] (E71.528)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E75.27 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E75.27 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E75.27 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Confirmed diagnosis of Pelizaeus-Merzbacher disease

PLP1 gene mutation analysis (duplications, point mutations, or deletions)

Brain MRI showing diffuse hypomyelination pattern

Form specification: classic (Type I), connatal (Type II), or transitional

MEAT Support

HCC Buddy guidance

Confirmed diagnosis of Pelizaeus-Merzbacher disease

PLP1 gene mutation analysis (duplications, point mutations, or deletions)

Brain MRI showing diffuse hypomyelination pattern

Form specification: classic (Type I), connatal (Type II), or transitional

Audit Caution

HCC Buddy guidance

Confusing Pelizaeus-Merzbacher disease (hypomyelinating) with metachromatic leukodystrophy or Krabbe disease (demyelinating)

Missing the characteristic nystagmus in infancy that is an early sign of PMD

Not recognizing PMD-like disease caused by GJC2 mutations (previously called PMD2) as a distinct entity

Failing to code spasticity, developmental delay, and other neurological complications separately

Common Mistakes

HCC Buddy guidance

E75.25 — Metachromatic leukodystrophy: a demyelinating disorder (myelin is formed then destroyed), not hypomyelinating

E75.23 — Krabbe disease: demyelinating leukodystrophy with different pathogenesis

E75.28 — Canavan disease: different leukodystrophy with spongy degeneration

G37.0 — Diffuse sclerosis of central nervous system: acquired demyelination, not genetic hypomyelination

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is E75.27 an HCC code?

No. E75.27 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.

HCC Category Mapping

RxHCCHCC 41, Lysosomal Storage Disorders

0.000

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.

Work E75.27 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E75.27

For E75.27to 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 E75.27 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E75.27 is the ICD-10-CM diagnosis code for pelizaeus-merzbacher disease. A rare inherited neurological disorder affecting the development and maintenance of myelin (the protective coating around nerve fibers), causing progressive weakness and loss of motor control. E75.27 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering metabolic disorders (e70-e88).

E75.27 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

Does not map to any HCC in V24, V28, or ESRD models. Maps only to RxHCC 41 (Rheumatoid Arthritis and Specified Autoimmune Disorders). No primary RAF weight in standard risk adjustment models despite significant disability and care needs. Coders reviewing E75.27 should check whether additional documentation would support a more specific child code in the same hierarchy that does map to a payment HCC, capturing the correct specificity is the highest-impact RAF improvement available within accurate coding.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E75.27 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document the specific type: classic, connatal, or transitional form to support medical necessity
•Link to associated neurological complications such as spasticity or developmental delays

Clinical Significance

Pelizaeus-Merzbacher disease is an X-linked hypomyelinating disorder caused by PLP1 gene mutations affecting proteolipid protein production, which is essential for myelin formation. Unlike demyelinating leukodystrophies, myelin is never properly formed. Patients develop nystagmus, spasticity, ataxia, and cognitive impairment. The classic form allows survival into adulthood, while the connatal form is more severe with limited life expectancy.

Documentation Requirements

✓Confirmed diagnosis of Pelizaeus-Merzbacher disease
✓PLP1 gene mutation analysis (duplications, point mutations, or deletions)
✓Brain MRI showing diffuse hypomyelination pattern
✓Form specification: classic (Type I), connatal (Type II), or transitional
✓Neurological assessment including nystagmus, spasticity, and developmental status
✓X-linked inheritance pattern documentation and family history

Commonly Confused Codes

•E75.25: Metachromatic leukodystrophy: a demyelinating disorder (myelin is formed then destroyed), not hypomyelinating
•E75.23: Krabbe disease: demyelinating leukodystrophy with different pathogenesis
•E75.28: Canavan disease: different leukodystrophy with spongy degeneration
•G37.0: Diffuse sclerosis of central nervous system: acquired demyelination, not genetic hypomyelination
•G11.1: Early-onset cerebellar ataxia: ataxia is a feature of PMD, not the primary diagnosis