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 2026. 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.
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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
ICD-10 codes Q90-Q99 cover a diverse set of chromosomal abnormalities not elsewhere classified, including well-known conditions like Down syndrome (Q90), Turner’s syndrome (Q96), and Klinefelter syndrome (Q98.0). These codes specifically categorize various trisomies, monosomies, partial deletions, duplications, balanced rearrangements, and sex chromosome anomalies, making them essential for precise diagnosis and documentation of genetic disorders.
This range includes distinct subtypes such as nonmosaic and mosaic forms of trisomy 21, 18, and 13, often referred to by synonyms like Trisomy 21- meiotic nondisjunction (Q90.0) and Down syndrome. Codes like Q92 describe other autosomal trisomies or partial trisomies with extensive synonyms listing specific partial duplications. The Q93 series addresses monosomies and deletions with famous examples like Wolf Hirschhorn syndrome (Q93.3) and Cri du chat syndrome (Q93.4). Balanced translocations and marker chromosomes have specific codes (Q95). Sex chromosome abnormalities, such as Turner syndrome (Q96), Triple X syndrome (Q97.0), and male karyotype anomalies including Klinefelter syndrome (Q98), are detailed with variants and mosaics. The final block Q99 covers other chromosomal anomalies including Fragile X syndrome (Q99.2) and unspecified chromosomal abnormalities, supporting nuanced genetic coding for diverse clinical scenarios.
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 2026. 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 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
