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ICD-10-CM 2027 diagnosis code

Q99Other chromosome abnormalities, not elsewhere classified

Not billable — use a more specific code

Q99 is a header code, so it can't be reported by itself. Choose one of the 5 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About Q99

Q99 is the ICD-10-CM diagnosis code for other chromosome abnormalities, not elsewhere classified. It belongs to block Q90-Q99 (chromosomal abnormalities, not elsewhere classified) and chapter 17 (congenital malformations, deformations, chromosomal abnormalities, and genetic disorders). It is a header code, so it can't be reported by itself; one of its 5 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: Q99.0 (XY), Q99.1 (hermaphrodite), Q99.2 (chromosome), Q99.8 (abnormalities) and Q99.9 (unspecified).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under Q99

Notes that apply from higher levels

Instructions written at a parent level also apply to Q99.

Broader instructions also apply from Q90-Q99 Chromosomal abnormalities, not elsewhere classified and Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders.

Codes whose notes reference Q99

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about Q99

Is Q99 billable?

No. Q99 is a header code. Report one of its more specific subcodes instead.