Q99Header code — not billable
Other chromosome abnormalities, not elsewhere classified
- Chapter
- 17. Congenital malformations, deformations and chromosomal abnormalities
- Category
- Q99
- Effective date
- October 1, 2026
Related codes in category Q99
Q99.0Chimera 46, XX/46, XYYesQ99.146, XX true hermaphroditeYesQ99.2Fragile X chromosomeYesQ99.8Other specified chromosome abnormalitiesQ99.81Usher syndromeQ99.811Usher syndrome, type 1YesQ99.812Usher syndrome, type 2YesQ99.813Usher syndrome, type 3YesQ99.818Other Usher syndromeYesQ99.819Usher syndrome, unspecifiedYesQ99.89Other specified chromosome abnormalitiesYesQ99.9Chromosomal abnormality, unspecifiedYes
Frequently asked questions
What is ICD-10 code Q99?
Q99 is an ICD-10-CM diagnosis code for Other chromosome abnormalities, not elsewhere classified.
Is Q99 a billable code?
No. Q99 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is Q99 in?
Q99 falls under Chapter 17: Congenital malformations, deformations and chromosomal abnormalities.
When did Q99 become effective?
Q99 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to Q99?
Q99 belongs to category Q99, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.