Chromosomal abnormalities, not elsewhere classified (Q90-Q99) ICD-10-CM
The Q90–Q99 section covers chromosomal abnormalities, not elsewhere classified with 88 ICD-10-CM diagnosis codes, of which 74 are billable in fiscal year 2027. The section is organized into the 9 code ranges listed below.
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
- mitochondrial metabolic disorders E88.4
Code Ranges in This Section 9 ranges · 88 codes
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About the Q90–Q99 Code Range
Chromosome abnormalities here include named syndromes, changes involving chromosomes other than sex chromosomes, and sex chromosome abnormalities.
Q90 groups Down syndrome, while Q91 separates trisomy 18 from trisomy 13. Both subdivide by chromosome pattern, with an option when the form is unspecified. Q92 groups other trisomies and partial trisomies, while Q93 groups missing chromosomes or chromosome segments. Q95 groups balanced chromosome rearrangements and structural markers.
Q96 groups Turner syndrome by chromosome pattern. Q97 and Q98 separate other sex chromosome abnormalities by female or male phenotype, meaning observable characteristics. Q99 groups other chromosome abnormalities, including fragile X chromosome and unspecified abnormalities.
FY 2027 changes: The FY 2027 ICD-10-CM update, effective October 1, 2026, deleted Q99.8.
Questions About This Page
How many codes are in the Q90-Q99 range?
The Q90-Q99 range contains 88 ICD-10-CM diagnosis codes in FY 2027. 74 of them are billable, and the rest are category headers that organize the section.
What conditions does Q90-Q99 cover?
The range covers chromosomal abnormalities, not elsewhere classified. The code ranges listed above break it into groups of related conditions, and each one links to its own page with the full code list.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
