Q90.9 — Down syndrome, unspecified

Q90.9

ICD-10 Chapter 17: Congenital & Genetic Disorders — illustrative image — Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00–QA1) — illustrative image

What this code means

Down syndrome is a genetic condition caused by an extra copy of chromosome 21, affecting development and learning; type unspecified.

Also called: down syndrome, trisomy 21.

When this code is used

Used for Down syndrome, unspecified.

Where it sits in ICD-10-CM

Code Q90.9 belongs to Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders, which covers codes Q00–QA1 in the FY2027 ICD-10-CM tabular list. The official description above is copied verbatim from the CDC/NCHS FY2027 code file.

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Frequently asked questions

What is ICD-10-CM code Q90.9?

Q90.9 is the ICD-10-CM diagnosis code for “Down syndrome, unspecified”. Down syndrome is a genetic condition caused by an extra copy of chromosome 21, affecting development and learning; type unspecified.

When is code Q90.9 used?

Used for Down syndrome, unspecified. It belongs to Chapter 17 of ICD-10-CM (Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders).

This guide explains ICD-10-CM codes in plain language for patients, students and other readers. It is educational information only — not coding, billing or medical advice. The code recorded for any real encounter is assigned from the full clinical documentation by the treating team and qualified coders, and only they can decide which code fits a specific case.