G90.1 ICD-10-CM Code: Familial dysautonomia [Riley-Day]
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Other disorders of the nervous system (G89-G99)
G90.1
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceFamilial dysautonomia [Riley-Day]
A rare inherited disorder affecting the autonomic nervous system, causing problems with blood pressure regulation, temperature control, and pain sensation, typically beginning in infancy.
Buddy Insight
Familial dysautonomia (Riley-Day syndrome) is a rare autosomal recessive genetic disorder primarily affecting the Ashkenazi Jewish population, causing severe dysfunction of the autonomic and sensory nervous systems.
CMS-HCC V28
MappedHCC 182
RAF 0.282
CMS-HCC V24
MappedHCC 72
RAF 0.464
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 72
RAF 0.0
RXHCC
MappedHCC 155
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for G90.1 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G90.1 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G90.1 in this effective period.
Excludes 1
Official- dysfunction of the autonomic nervous system due to alcohol (G31.2)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for G90.1 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G90.1 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G90.1 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 G90.1 an HCC code?
Yes. G90.1 maps to Spinal Cord Disorders/Injuries under the CMS-HCC V28 risk adjustment model (and Spinal Cord Disorders/Injuries under V24).
HCC Category Mapping
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.
MEAT Criteria for G90.1
For G90.1to 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 G90.1 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
G90.1 is the ICD-10-CM diagnosis code for familial dysautonomia [riley-day]. A rare inherited disorder affecting the autonomic nervous system, causing problems with blood pressure regulation, temperature control, and pain sensation, typically beginning in infancy. G90.1 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering other disorders of the nervous system (g89-g99).
Under the CMS-HCC V28 risk adjustment model, G90.1 maps to Spinal Cord Disorders/Injuries (HCC 182) with a community, non-dual, aged base RAF weight of 0.282. Under the older V24 model, G90.1 mapped to the same category but with a base RAF weight of 0.464, V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
This is a genetic condition; document family history when available. Because G90.1 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G90.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a genetic condition; document family history when available
- •Often requires multidisciplinary management; coordinate coding with other system manifestations
Clinical Significance
Familial dysautonomia (Riley-Day syndrome) is a rare autosomal recessive genetic disorder primarily affecting the Ashkenazi Jewish population, causing severe dysfunction of the autonomic and sensory nervous systems. It significantly impacts risk adjustment due to chronic multi-system involvement requiring lifelong management. Patients face life-threatening complications including aspiration pneumonia, dysautonomic crises, and cardiovascular instability.
Documentation Requirements
- ✓Genetic confirmation or family history consistent with hereditary sensory and autonomic neuropathy type III
- ✓Documented autonomic dysfunction symptoms (orthostatic hypotension, temperature dysregulation, excessive sweating, blood pressure lability)
- ✓Sensory deficits including decreased pain and temperature perception
- ✓Assessment of current functional status and management plan
- ✓Documentation of ongoing monitoring and treatment for autonomic crises
Commonly Confused Codes
- •G90.09: Other idiopathic peripheral autonomic neuropathy: used for non-hereditary autonomic neuropathies without a genetic basis
- •G90.3: Multi-system degeneration of the autonomic nervous system: acquired degenerative condition, not hereditary
- •G60.0: Hereditary motor and sensory neuropathy: broader hereditary neuropathy category (e.g., Charcot-Marie-Tooth) without the autonomic component
- •G90.59: Other complex regional pain syndrome: involves autonomic features but is acquired and typically post-traumatic