Billable / Specific Code
ICD-10-CM Q90.1 is the diagnosis code for Trisomy 21, mosaicism (mitotic nondisjunction). This code falls under the section "Chromosomal abnormalities, not elsewhere classified" within Chapter 17 — Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0). It is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes. Medical coders and healthcare providers use this code to document and classify diagnoses in electronic health records, insurance claims, and clinical databases.
Always refer to the official ICD-10-CM Tabular List for complete coding guidelines. Ensure documentation supports the specificity of the code selected. When in doubt, consult a certified medical coder or the latest CMS guidelines.
Understanding where Q90.1 sits in the ICD-10-CM classification helps ensure proper coding:
Yes, Q90.1 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
Q90.1 is the ICD-10-CM diagnosis code for "Trisomy 21, mosaicism (mitotic nondisjunction)". It is used by healthcare providers to classify and document this condition in medical records and insurance claims.
The parent code of Q90.1 is Q90 ("Down syndrome"). Q90.1 provides a more specific classification within this category.
Q90.1 is located in Section Q90-Q99 — "Chromosomal abnormalities, not elsewhere classified" within Chapter 17 of the ICD-10-CM Tabular List.
Use Q90.1 when the patients documented diagnosis matches "Trisomy 21, mosaicism (mitotic nondisjunction)" and the clinical documentation supports this level of specificity. Always verify with the latest ICD-10-CM guidelines and payer requirements.
The ICD-10-CM code for Trisomy 21, mosaicism (mitotic nondisjunction) is Q90.1.
Yes, Q90.1 can be used as a primary diagnosis code since it is billable and specific.
Q90.1 is in Chapter 17 of the ICD-10-CM Tabular List.
Yes, Q90.1 is a valid ICD-10-CM code for the 2026 fiscal year, subject to official CMS updates.