Q93.82
BillableWilliams syndrome
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Q93.82 an HCC code?
No. Q93.82 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
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 Q93.82
For Q93.82to 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 Q93.82 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Q93.82 is the ICD-10-CM diagnosis code for williams syndrome. Williams syndrome is a genetic disorder caused by a microdeletion on chromosome 7, characterized by distinctive facial features, heart defects (especially supravalvular aortic stenosis), intellectual disability, and a unique personality with strong verbal and social abilities. Q93.82 sits in the ICD-10-CM chapter for congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (q00-qa0), within the section covering chromosomal abnormalities, not elsewhere classified (q90-q99).
Q93.82 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.
This code maps to RxHCC 148 (Mild Intellectual Disabilities) with a RAF weight of 0.0 in the RxHCC model. Although it doesn't contribute to risk adjustment scoring, it identifies patients with Williams syndrome who typically require cardiac medications, calcium metabolism management, and medications for anxiety or attention issues.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Q93.82 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Code associated cardiovascular abnormalities separately, particularly supravalvular aortic stenosis which is common in this syndrome
- •Document the characteristic personality and cognitive profile; patients often have relative strengths in verbal abilities despite intellectual disability
Clinical Significance
Williams syndrome is a genetic disorder caused by a microdeletion on chromosome 7 characterized by distinctive facial features, cardiovascular abnormalities (especially supravalvular aortic stenosis), intellectual disability with relative strengths in language, and a unique overly social personality. This condition requires cardiac monitoring, developmental support, and management of hypercalcemia.
Documentation Requirements
- ✓Genetic testing confirming 7q11 microdeletion
- ✓Distinctive facial features (elfin-like appearance)
- ✓Cardiovascular abnormalities (especially supravalvular aortic stenosis)
- ✓Intellectual disability with language strengths noted
- ✓Overly friendly, social personality
- ✓Hypercalcemia or calcium metabolism abnormalities
- ✓Growth patterns and failure to thrive
- ✓Associated medical conditions
Commonly Confused Codes
- •Q9388 — Use specific Williams syndrome code when 7q11 deletion confirmed
- •Q9359 — Other deletions don't have Williams syndrome phenotype
- •Q9381 — Velocardiofacial syndrome has different genetic cause and features
- •I35.1 — Aortic stenosis may be present but genetic cause is key