Q99.8

Non-Billable

ChapterQ00–Q99

Ranksubcategory

Official Description

Other specified chromosome abnormalities

Metadata & Insights

•2026 ICD-10-CM Edition - Effective October 1, 2025.
•Non-billable category (requires more specific sub-code).
•Chapter 17: Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-Q99).

General instructions are available for the parent sections:

View CH17 Notes View Q90-Q99 Notes

Clinical Hierarchy

CH17Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0)

Q90-Q99Chromosomal abnormalities, not elsewhere classified (Q90-Q99)

Q99Other chromosome abnormalities, not elsewhere classified

Q99.8Other specified chromosome abnormalities

Q99.81Usher syndrome

Q99.89Other specified chromosome abnormalities

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to Q99.8:

blockQ90-Q99

Chromosomal abnormalities, not elsewhere classified (Q90-Q99)

View context instructions

chapterCH17

Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0)

View context instructions

Alphabetic Index Mentions

These are Diagnosis Index lookup paths that route to Q99.8. Use them as entry terms for search, then confirm final coding instructions in the Tabular List and notes above.

12 raw paths

Abnormal, abnormality, abnormalities2 unique routes

chromosome, chromosomal(2 variants)

sex→Q99.8

specified NEC→Q99.8

Additional1 unique routes

chromosome (s)→Q99.8

Anomaly, anomalous (congenital) (unspecified type)1 unique routes

chromosomes, chromosomal

specified NEC→Q99.8

Syndrome7 unique routes

due to abnormality