Q99.8 – Other specified chromosome abnormalities

ICD-10-CM 2027 diagnosis code · Chromosomal abnormalities, not elsewhere classified

Non-billable header

ICD-10-CM code Q99.8

Code: Q99.8 (claims format: Q998)
Description: Other specified chromosome abnormalities
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 17. Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1)
Block: Q90-Q99 Chromosomal abnormalities, not elsewhere classified
Parent codes: Q99

Billable codes under Q99.8

Q99.8 is a header code and cannot be used on claims. Choose the most specific code:

Q99.81 – Usher syndromeHeader (more codes below)
Q99.89 – Other specified chromosome abnormalitiesBillable

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Block Q90-Q99

Excludes2 (not included here):

mitochondrial metabolic disorders (E88.4-)

Index terms for Q99.8

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in Q99

Q99.0 – Chimera 46, XX/46, XYBillable
Q99.1 – 46, XX true hermaphroditeBillable
Q99.2 – Fragile X chromosomeBillable
Q99.9 – Chromosomal abnormality, unspecifiedBillable

Frequently asked questions

What is ICD-10 code Q99.8?

Q99.8 is the ICD-10-CM code for other specified chromosome abnormalities, in the block Q90-Q99 (Chromosomal abnormalities, not elsewhere classified).

Is Q99.8 a billable code?

No. Q99.8 is a header code with more specific child codes; report one of the billable codes listed above.

What category does Q99.8 belong to?

It belongs to category Q99 – Other chromosome abnormalities, not elsewhere classified.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.