Chapter 17

Q00–Q99: Congenital Malformations, Deformations and Chromosomal Abnormalities

Congenital Malformations, Deformations and Chromosomal Abnormalities diagnostic classification updated for 2026.

Chapter Instructions

Excludes2(Not included here. Code separately if applicable.)
  • inborn errors of metabolism (E70-E88)
Internal Codes
  • Q98.7|

    Male with sex chromosome mosaicism

  • Q98.8|

    Other specified sex chromosome abnormalities, male phenotype

  • Q98.9|

    Sex chromosome abnormality, male phenotype, unspecified

  • Q99|

    Other chromosome abnormalities, not elsewhere classified

  • Q99.0|

    Chimera 46, XX/46, XY

  • Q99.1|

    46, XX true hermaphrodite

  • Q99.2|

    Fragile X chromosome

  • Q99.8|

    Other specified chromosome abnormalities

  • Q99.81|

    Usher syndrome

  • Q99.811|

    Usher syndrome, type 1

  • Q99.812|

    Usher syndrome, type 2

  • Q99.813|

    Usher syndrome, type 3

  • Q99.818|

    Other Usher syndrome

  • Q99.819|

    Usher syndrome, unspecified

  • Q99.89|

    Other specified chromosome abnormalities

  • Q99.9|

    Chromosomal abnormality, unspecified

  • QA0|

    Neurodevelopmental disorders related to specific genetic pathogenic variants

  • QA0.0|

    Neurodevelopmental disorders related to pathogenic variants in specific genes

  • QA0.01|

    Neurodevelopmental disorders related to pathogenic variants in certain specific genes

  • QA0.010|

    Neurodevelopmental disorders, related to pathogenic variants in ion channel genes

  • QA0.0101|

    SCN2A-related neurodevelopmental disorder

  • QA0.0102|

    CACNA1A-related neurodevelopmental disorder

  • QA0.0109|

    Neurodevelopmental disorder related to pathogenic variant in other ion channel gene

  • QA0.011|

    Neurodevelopmental disorders, related to pathogenic variants in glutamate receptor genes

  • QA0.012|

    Neurodevelopmental disorders, related to pathogenic variants in other receptor genes

  • QA0.013|

    Neurodevelopmental disorders, related to pathogenic variants in other transporter and solute carrier genes

  • QA0.0131|

    SLC6A1-related disorder

  • QA0.0139|

    Neurodevelopmental disorder, related to pathogenic variant in other transporter or solute carrier gene

  • QA0.014|

    Neurodevelopmental disorders, related to pathogenic variants in synapse related genes

  • QA0.0141|

    Syntaxin-binding protein 1-related disorder

  • QA0.0142|

    DLG4-related synaptopathy

  • QA0.0149|

    Neurodevelopmental disorder, related to pathogenic variant in other synapse related gene

  • QA0.015|

    Neurodevelopmental disorders, related to genes associated with transcription and gene expression

  • QA0.0151|

    FOXG1 syndrome

  • QA0.0159|

    Neurodevelopmental disorder, related to other genes associated with transcription and gene expression

  • QA0.8|

    Other neurodevelopmental disorders related to pathogenic variants in other specific genes

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