2027 ICD-10-CM Diagnosis Code G90.1Familial dysautonomia [Riley-Day]

ICD-10-CM Codes›G00–G99›G89-G99›G90

ICD-10-CM G90.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G90.1 is a billable ICD-10-CM diagnosis code for familial dysautonomia [Riley-Day]. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93, 791, 793. Coders also document this condition as familial dysautonomia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).

For Medicare Advantage risk adjustment, G90.1 maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries) under the V28 model, adding a risk factor of about 0.478 for a community, non-dual, aged beneficiary in payment year 2027.

Code Identity

ICD-10-CM Code
G90.1
Billable Status
Yes — Valid for Submission
Code Describes
Familial dysautonomia [Riley-Day]
Short Description
Familial dysautonomia [Riley-Day]
Same as the full description in the CMS dataset.
Parent Code
G90
Disorders of autonomic nervous system

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG89-G99Other disorders of the nervous system
CategoryG90Disorders of autonomic nervous system
This CodeG90.1Familial dysautonomia [Riley-Day]

Medicare Risk Adjustment (HCC)Billing

G90.1 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.

CMS-HCC V28 Category (Payment Model)
HCC 182— Spinal Cord Disorders/Injuries
Payment HCC · PY 2027 one of 251 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.478
community, non-dual, aged · ranges 0.270–0.478 across segments
Hierarchy
Superseded by HCC 180, HCC 181, HCC 191, and HCC 192
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 72
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 72 · ESRD (V21): HCC 72 · ESRD (V24): HCC 72
ESRD V21 weights: 0.102 dialysis, 0.256–0.456 functioning graft · ESRD V24 weights: 0.099 dialysis, 0.222–0.523 functioning graft
Part D (RxHCC)
RxHCC 155 — Spinal Cord Disorders
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Familial dysautonomia
  • Hereditary dysautonomia with motor neuropathy

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G90.1: its own notes plus those printed at G90 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From G90 Disorders of autonomic nervous system applies to 21 codes
  • dysfunction of the autonomic nervous system due to alcohol (G31.2)

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.

From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • 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)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G90.1, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming G90.1: they are not reported together with it, unless the two conditions are unrelated.

  • Q85 Phakomatoses, not elsewhere classified
    familial dysautonomia [Riley-Day] (G90.1)

Excludes2 1

These codes carry an Excludes2 note naming G90.1: its condition is not part of those codes, and both may be reported when the patient has both.

  • Q07 Other congenital malformations of nervous system
    familial dysautonomia [Riley-Day] (G90.1)

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR NVS006
Other nervous system disorders (often hereditary or degenerative)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Autonomic Nervous System Diseases

    diseases of the autonomic nervous system, including sympathetic, parasympathetic, and enteric nervous systems.

  • Dysautonomia, Familial

    an autosomal disorder of the peripheral and autonomic nervous systems limited to individuals of ashkenazic jewish descent. clinical manifestations are present at birth and include diminished lacrimation, defective thermoregulation, orthostatic hypotension (hypotension, orthostatic), fixed pupils, excessive sweating, loss of pain and temperature sensation, and absent reflexes. pathologic features include reduced numbers of small diameter peripheral nerve fibers and autonomic ganglion neurons. (from adams et al., principles of neurology, 6th ed, p1348; nat genet 1993;4(2):160-4)

Patient EducationClinical

Autonomic Nervous System Disorders

Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart and the widening or narrowing of your blood vessels. When something goes wrong in this system, it can cause serious problems, including:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G90.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
742.8 Nervous system anom NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About G90.1Overview

What is the ICD-10 code for familial dysautonomia [Riley-Day]?

The ICD-10-CM code for familial dysautonomia [Riley-Day] is G90.1 (sometimes written as G901). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G90.1 (Disorders of autonomic nervous system) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report familial dysautonomia [Riley-Day] on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does G90.1 group to?

When familial dysautonomia [Riley-Day] is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 91, 92, 93, with relative weights from 0.7783 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.

Can G90.1 be reported with G31.2?

Not as a rule. The Excludes1 note at G90, which applies to G90.1, lists "dysfunction of the autonomic nervous system due to alcohol (G31.2)". 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 is the ICD-9 equivalent of G90.1?

Under the General Equivalence Mappings, familial dysautonomia [Riley-Day] converts to ICD-9-CM 742.8 (nervous system anom NEC). The mapping is approximate, so confirm the match fits the documentation.

What HCC is G90.1?

G90.1 (familial dysautonomia [Riley-Day]) maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries), commonly written as HCC 182, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 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 155.

Does G90.1 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, G90.1 adds a risk adjustment factor of about 0.478 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.270 to 0.478 depending on the payment segment). A more severe related category (HCC 180, HCC 181, HCC 191, and HCC 192) supersedes it when both are reported. See the full factor table on the HCC 182 category page.