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    v1.0.28
    OpenPayerBilling CodesChromosomal abnormalities, not elsewhere classifiedICD-10-CM q90-down-syndrome
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    ICD-10-CM Code For Down Syndrome: Group Overview

    The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group Q90 includes diagnoses related to Down syndrome, including nonmosaic trisomy 21, mosaic trisomy 21, and translocation trisomy 21, covering the spectrum of chromosomal abnormalities associated with chromosome 21. These ICD-10-CM diagnosis codes are used to document congenital chromosomal abnormalities that impact development and multiple organ systems, capturing disease severity, associated congenital anomalies, and clinical complexity relevant to this group. Accurate coding within the ICD-10-CM Q90 group supports proper claim adjudication, complete clinical documentation, and appropriate reimbursement.

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    ICD-10-CM Q90: Down Syndrome Overview

    The ICD-10-CM Q90 group includes congenital chromosomal abnormalities characterized by trisomy of chromosome 21 and related variants. These diagnoses target genetic and developmental conditions that affect multiple organ systems, including cardiac, gastrointestinal, and neurologic function. Accurate coding is important to reflect clinical complexity and to support appropriate reimbursement and care planning.

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    When to Use

    Use a code from this group when a confirmed diagnosis of Down syndrome or a specified trisomy 21 variant is documented by a clinician or genetic testing. Codes from this group are appropriate for encounters addressing congenital features, associated anomalies, or management related to the chromosomal diagnosis.

    ICD-10-CM Codes

    4 rows

    ICD-10-CM CodeDescription
    Q90.0Trisomy 21, nonmosaicism (meiotic nondisjunction)
    Q90.1Trisomy 21, mosaicism (mitotic nondisjunction)
    Q90.2Trisomy 21, translocation
    Q90.9Down syndrome, unspecified

    DRG Codes

    1 rows

    DRG CodeDescription
    884Organic Disturbances and Intellectual Disability

    Typical Clinical Scenarios

    • A newborn delivered at term is noted on physical exam to have hypotonia, upslanting palpebral fissures, a flat nasal bridge, and single palmar creases. The infant is admitted to the neonatal unit for genetic evaluation and karyotype confirms trisomy 21; the diagnosis is recorded to capture the congenital chromosomal condition present at birth. Typical codes: Q90.0, Q90.9.
    • A 12-year-old child with known Down syndrome presents to primary care for routine health maintenance and to address chronic developmental delays and congenital cardiac disease follow-up; the visit documents baseline intellectual disability and long-term management needs related to the chromosomal condition. Typical codes: Q90.1, Q90.9.
    • A 45-year-old adult with previously diagnosed Down syndrome is evaluated in the emergency department for progressive memory loss, behavioral changes, and suspected early-onset Alzheimer disease; the chromosomal abnormality is listed as a comorbidity impacting assessment and care planning. Typical codes: Q90.2, Q90.9.

    Related Codes

    Q91-TRISOMY-18-AND-TRISOMY-13

    ICD-10-CM Code For Trisomy 18 And Trisomy 13: Group Overview

    Q92-OTHER-TRISOMIES-AND-PARTIAL-TRISOMIES

    ICD-10-CM Code For Other Trisomies And Partial Trisomies Of The Autosomes Not Elsewhere Classified: Group Overview

    Q93-MONOSOMIES-AND-DELETIONS

    ICD-10-CM Code For Monosomies And Deletions From The Autosomes Not Elsewhere Classified: Group Overview

    Q95-BALANCED-REARRANGEMENTS-AND-STRUCTURAL-MARKERS

    ICD-10-CM Code For Balanced Rearrangements And Structural Markers Not Elsewhere Classified: Group Overview

    Q96-TURNERS-SYNDROME

    ICD-10-CM Code For Turner's Syndrome: Group Overview

    Q97-OTHER-SEX-CHROMOSOME-ABNORMALITIES-FEMALE-PHENOTYPE

    ICD-10-CM Code For Other Sex Chromosome Abnormalities Female Phenotype Not Elsewhere Classified: Group Overview

    Q98-OTHER-SEX-CHROMOSOME-ABNORMALITIES-MALE-PHENOTYPE

    ICD-10-CM Code For Other Sex Chromosome Abnormalities Male Phenotype Not Elsewhere Classified: Group Overview

    Q99-OTHER-CHROMOSOME-ABNORMALITIES-NOT-ELSEWHERE-CLASSIFIED

    ICD-10-CM Code For Other Chromosome Abnormalities, Not Elsewhere Classified: Group Overview

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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