ICD-10 · PDGM grouping
Q99 Other chromosome abnormalities, not elsewhere classified
All 10 codes in the Q99 family, with the PDGM clinical group, comorbidity subgroup and primary-position rule CMS assigns, read from the CMS grouper crosswalk v07.2.26 and the CDC FY2027 code file.
Codes in family
10
Can lead a claim
9
Cannot lead a claim
1
What CMS assigns to Q99
9 of the 10 codes group to MMTA - Other; 1 is assigned no clinical group. None of the 10 is assigned a comorbidity subgroup. 9 of the 10 can lead a claim.
Every code in Q99
Descriptions are CDC’s FY2027 wording; where CMS’s grouper abbreviates one, its form is shown beneath.
| Code | Description | Primary position | Clinical group | Comorbidity subgroup |
|---|---|---|---|---|
| Q99.0 | Chimera 46, XX/46, XY | Can lead a claim | A | None |
| Q99.1 | 46, XX true hermaphrodite | Can lead a claim | A | None |
| Q99.2 | Fragile X chromosome | Can lead a claim | A | None |
| Q99.8 Other specified chromosome abnormalities | ||||
| Q99.81 Usher syndrome | ||||
| Q99.811 | Usher syndrome, type 1 | Can lead a claim | A | None |
| Q99.812 | Usher syndrome, type 2 | Can lead a claim | A | None |
| Q99.813 | Usher syndrome, type 3 | Can lead a claim | A | None |
| Q99.818 | Other Usher syndrome | Can lead a claim | A | None |
| Q99.819 | Usher syndrome, unspecified | Can lead a claim | A | None |
| Q99.89 | Other specified chromosome abnormalities | Can lead a claim | A | None |
| Q99.9 | Chromosomal abnormality, unspecified | Cannot lead a claimPrincipal diagnosis not assigned to a clinical group | None | None |
Sources: CMS HH PPS Grouper Software v07.2.26, effective 2026-10-01, for the clinical group, comorbidity subgroup, code-first conventions and primary-position flags; CDC NCHS ICD-10-CM FY2027 code descriptions for the family title and code wording. This is the crosswalk Medicare runs a claim through. Grouping also depends on admission source, timing, the OASIS functional items and the rest of the diagnosis list.
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