Q90.1 Trisomy 21, mosaicism (mitotic nondisjunction)

BillableNo payment HCCChapter 17

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Instructional notes

Chapter 17

Excludes2Not included here: the patient may have both; report both when both are present.

inborn errors of metabolism (E70-E88)

Notes

Codes from this chapter are not for use on maternal records

Section Q90-Q99

Excludes2Not included here: the patient may have both; report both when both are present.

mitochondrial metabolic disorders (E88.4-)

Q90

Use additional codeAdd a second code for the full picture.

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-)

Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1) · Q90-Q99 Chromosomal abnormalities, not elsewhere classified (Q90-Q99)

Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.

Coverage and payment depend on the claim details; confirm with the Medicare Administrative Contractor.