Q99.818 ICD-10-CM Code: Other Usher syndrome
HCC Buddy Code Card
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FY 2026 Apr update / Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0) / Chromosomal abnormalities, not elsewhere classified (Q90-Q99)
Q99.818
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther Usher syndrome
A genetic disorder causing progressive hearing loss and vision loss (retinitis pigmentosa) that does not fit the typical patterns of types 1, 2, or 3 Usher syndrome.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
MappedHCC 97
Varies by metal level
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
Official- Usher syndrome, type 4
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for Q99.818 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for Q99.818 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for Q99.818 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for Q99.818 in this effective period.
Use Additional
Official- code to identify any auditory and visual manifestations
Code Also
OfficialICD-10-CM does not list Code Also instructions for Q99.818 in this effective period.
Buddy Documentation Tip
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is Q99.818 an HCC code?
No. Q99.818 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
- Code
- Q99.818
- Description
- Other Usher syndrome
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
Q99.818 is the ICD-10-CM diagnosis code for other usher syndrome. A genetic disorder causing progressive hearing loss and vision loss (retinitis pigmentosa) that does not fit the typical patterns of types 1, 2, or 3 Usher syndrome. Q99.818 sits in the ICD-10-CM chapter for congenital malformations, deformations and chromosomal abnormalities (q00-qa0), within the section covering chromosomal abnormalities, not elsewhere classified (q90-q99).
Q99.818 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.
Use this code only when Usher syndrome is confirmed but does not meet criteria for types 1, 2, or 3.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Q99.818 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when Usher syndrome is confirmed but does not meet criteria for types 1, 2, or 3
- •Document the specific clinical features and genetic findings that support the Usher syndrome diagnosis