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HCC 200: Friedreich and Other Hereditary Ataxias; Huntington Disease

HCC 200, Friedreich and Other Hereditary Ataxias; Huntington Disease, is one of the 115 payment categories in the CMS-HCC V28 model. 17 ICD-10-CM codes map to it in the payment year 2027 mapping, and a documented diagnosis in the category adds a relative factor of 0.279 to the risk score of a community, non-dual, aged beneficiary (0.208 disabled, 0.000 institutional). It sits at the top of its hierarchy, so no other category overrides it.

QuickIntell editorial content · Legacy registry date · Review not verified

Data effective
Data currency: ICD-10-CM to HCC mapping PY2027 initial (effective dates of service 2026, payment year 2027); CMS-HCC V28 model software V2826.115.T2 (effective payment year 2027). Next CMS release: PY2027 midyear final mapping (spring 2027) and PY2028 proposed model (February 2027).
Mapped ICD-10-CM codes
17
Factor, community non-dual aged
0.279
Factor, institutional
0.000
Hierarchy
Top of hierarchy

Relative factors by segment

Each segment is a separate regression; the factor is added to the beneficiary's demographic factors and other categories, then normalized and reduced by the coding intensity adjustment before it meets the plan's base rate. A factor of 1.000 equals the expected cost of an average beneficiary.

CMS-HCC V28 relative factors for HCC 200 by model segment
SegmentModel codeRelative factor
Community, non-dual, agedCNA_HCC2000.279
Community, non-dual, disabledCND_HCC2000.208
Community, full-benefit dual, agedCFA_HCC2000.165
Community, full-benefit dual, disabledCFD_HCC2000.281
Community, partial-benefit dual, agedCPA_HCC2000.050
Community, partial-benefit dual, disabledCPD_HCC2000.428
Long-term institutionalINS_HCC2000.000

Hierarchy

HCC 200 is not part of a hierarchy: it is paid whenever a mapped diagnosis is documented, independently of the beneficiary's other categories.

ICD-10-CM codes that map to HCC 200

17 codes map to this category in the PY2027 initial mapping, concentrated in the G11 (11), G93 (3), G10 (1), G31 (1), G90 (1) code families. Descriptions are the CMS mapping descriptions for the FY2026 code set; a code that is deleted or split in the October code update stays valid for dates of service before the change.

ICD-10-CM codes mapped to HCC 200 in the CMS PY2027 initial mapping
ICD-10-CMDescription
G10Huntington's disease
G110Congenital nonprogressive ataxia
G1110Early-onset cerebellar ataxia, unspecified
G1111Friedreich ataxia
G1119Other early-onset cerebellar ataxia
G112Late-onset cerebellar ataxia
G113Cerebellar ataxia with defective DNA repair
G114Hereditary spastic paraplegia
G115Hypomyelination - hypogonadotropic hypogonadism - hypodontia
G116Leukodystrophy with vanishing white matter disease
G118Other hereditary ataxias
G119Hereditary ataxia, unspecified
G3180Leukodystrophy, unspecified
G90BLMNB1-related autosomal dominant leukodystrophy
G9342Megalencephalic leukoencephalopathy with subcortical cysts
G9343Leukoencephalopathy with calcifications and cysts
G9344Adult-onset leukodystrophy with axonal spheroids

Where these codes sat in the V22 model

The V28 recalibration renumbered and regrouped categories; this table shows which legacy V22 categories the same ICD-10 codes belonged to, which is the quickest way to reconcile a V22-era HCC gap list with the current model.

V22 categories that the HCC 200 codes mapped to
V22 HCCCodes
7211
781

Capturing and defending the category

A category counts for a payment year when a mapped diagnosis is documented at least once during the data collection year by an acceptable provider type at a face-to-face or audio-video encounter, and when the note shows the condition was monitored, evaluated, assessed or treated. Chronic conditions do not carry forward: a category that is not re-documented in the year drops out of the score, which is why annual wellness visits and problem-list reconciliation are where most recapture happens. Risk adjustment data validation audits sample enrollees and ask for the medical record behind each submitted category; an unsupported category is removed and, under the extrapolation rules, the error rate is applied across the contract. The QuickIntell risk adjustment product surfaces suspected and unsupported categories from the chart, and the HCC hub lists every V28 category with its factor and code count.

Frequently asked questions

Which ICD-10 codes map to HCC 200?

17 ICD-10-CM codes map to HCC 200 in the CMS PY2027 initial mapping, for example G10 Huntington's disease; G110 Congenital nonprogressive ataxia; G1110 Early-onset cerebellar ataxia, unspecified; G1111 Friedreich ataxia. The full list is on this page; a code counts only when it is documented at a face-to-face or video encounter in the data collection year and supported by the record.

How much does HCC 200 add to a risk score?

The V28 relative factor for HCC 200 is 0.279 for a community, non-dual, aged beneficiary, 0.165 for full-benefit dual aged, 0.208 for non-dual disabled and 0.000 for long-term institutional members. A factor of 1.000 equals the expected annual cost of an average beneficiary, so the category's share of the payment follows the plan's base rate for that segment.

Does HCC 200 count together with related categories?

HCC 200 is not part of a hierarchy, so it is paid whenever it is documented regardless of which other categories the beneficiary has.

What has to be documented for HCC 200 to be valid?

The diagnosis must be recorded by an acceptable provider type during a face-to-face or audio-video encounter in the service year, with the note showing that the condition was monitored, evaluated, assessed or treated. Risk adjustment data validation audits recover payment for categories the record does not support, so the code on the claim and the assessment in the note must match.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-02. Verify against the primary file before billing or contracting decisions.

Disclaimer

Relative factors and mappings are reproduced from the CMS risk adjustment model files as an operational reference. Payment depends on the plan's base rate, normalization, the coding intensity adjustment and the enrollee's segment. Not legal, clinical or billing advice.