Q90.1

Trisomy 21, mosaicism (mitotic nondisjunction)

Billable code

This code does not map to a risk-adjusting HCC in the loaded models.

Coding notes

Excludes 1 never coded together · Excludes 2 may co-exist

Inherited from Q90Down syndrome
Use additional

code(s) to identify any associated degree of intellectual disabilities (F70-F79)

Code also

associated physical condition(s), such as atrioventricular septal defect (Q21.2-)

Inherited from Q90-Q99Chromosomal abnormalities, not elsewhere classified
Excludes 2

mitochondrial metabolic disorders (E88.4-)

Inherited from chapter 17Congenital malformations, deformations and chromosomal abnormalities
Excludes 2

inborn errors of metabolism (E70-E88)

Note

Codes from this chapter are not for use on maternal records

Official Guidelines for Q90.1

FY 2026 ›
I.C.17Chapter-specific guidanceChapter 17: Congenital malformations, deformations, and chromosomal abnormalities (Q00-QA1)

Sections that reference Q90.1

Sections whose FY 2026 text names Q90.1, its Q90 category, or a range containing it — the chapter guidance above is the authoritative source.

Find Q90.1 in the alphabetic index

6 index paths lead to this code