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  6. 2026 ICD-10-CM Code Q91

2026 ICD-10-CM Diagnosis Code Q91

Trisomy 18 and Trisomy 13

ICD-10-CM Code:
Q91
ICD-10 Code for:
Trisomy 18 and Trisomy 13
Is Billable?
Not Valid for Submission
Code Navigator:

Q91 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of trisomy 18 and trisomy 13. The code is not specific and is NOT valid for the year 2026 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

Specific Coding Applicable to Trisomy 18 and Trisomy 13

Non-specific codes like Q91 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for trisomy 18 and trisomy 13:

  • Use Q91.0 for Trisomy 18, nonmosaicism (meiotic nondisjunction) - BILLABLE CODE

  • Use Q91.1 for Trisomy 18, mosaicism (mitotic nondisjunction) - BILLABLE CODE

  • Use Q91.2 for Trisomy 18, translocation - BILLABLE CODE

  • Use Q91.3 for Trisomy 18, unspecified - BILLABLE CODE

  • Use Q91.4 for Trisomy 13, nonmosaicism (meiotic nondisjunction) - BILLABLE CODE

  • Use Q91.5 for Trisomy 13, mosaicism (mitotic nondisjunction) - BILLABLE CODE

  • Use Q91.6 for Trisomy 13, translocation - BILLABLE CODE

  • Use Q91.7 for Trisomy 13, unspecified - BILLABLE CODE

Code Classification

  • Congenital malformations, deformations and chromosomal abnormalities
    Q00-Q99
    • Chromosomal abnormalities, not elsewhere classified
      Q90-Q99
      • Trisomy 18 and Trisomy 13
        Q91

Patient Education


Genetic Disorders

What are genetic disorders?

Genetic disorders are health conditions caused by changes (also called mutations or variants) in your genes. Genes are parts of DNA found in your cells that carry instructions for how your body grows, develops, and functions. Many genes tell your body how to make proteins, which are needed for your body to work properly.

What causes genetic disorders?

A genetic disorder happens when a gene variant changes how a protein is made. The variant may cause the protein to work poorly or not be made at all. If genes don't make the right proteins, or don't make them correctly, it can lead to a genetic disorder.

Not all gene changes cause disease. Often, these changes have no effect. But sometimes, even a small change in DNA can affect how proteins are made.

Gene variants can be grouped into two main types:

  • Inherited variants (also called germline variants) are passed down from your parents. They come from egg or sperm cells.
  • Non-inherited (also called somatic variants) are not passed down from your parents. They happen during your lifetime. They may be caused by things like harmful chemicals or ultraviolet (UV) rays from the sun.

What are the types of genetic disorders?

Genetic disorders may be caused by:

  • Single gene disorders are caused by changes in one gene. Examples can include sickle cell anemia, where a change in a single gene can cause the condition, and Charcot-Marie-Tooth disease, where a variant in one of many different genes can cause the condition.
  • Chromosomal disorders are caused by missing, extra, or altered chromosomes. Chromosomes are structures that carry genes. These disorders involve changes in the number of chromosomes people have or changes in the structure of one or more chromosomes. An example is Down syndrome, which is caused by an extra copy of chromosome 21.
  • Complex (multifactorial) disorders are caused by changes in many genes. Each change alone may not cause the disease, but together they increase the risk. Lifestyle and environmental factors, such as exercise, diet, or exposure to pollutants, also play a role. Colon cancer is an example.

What are the different ways a genetic disorder can be inherited?

Some genetic conditions are passed down through families (inherited) in one of several patterns, depending on the specific gene involved.

Patterns of inheritance can include:

  • Dominant means you only need one changed gene to cause the condition.
  • Recessive means you need two changed copies of the gene (one from each parent) for the condition to occur.
  • X-linked conditions involve genes located on the X chromosome. These conditions often affect males more frequently.
  • Mitochondrial conditions are passed down by the mother.

How are genetic disorders diagnosed?

Your health care provider may check for a genetic condition based on:

  • A physical examination.
  • Your personal medical history.
  • Your family health history.
  • Laboratory tests, including genetic testing.

NIH: National Library of Medicine


[Learn More in MedlinePlus]

Trisomy 18

Trisomy 18, also called Edwards syndrome, is a chromosomal condition associated with abnormalities in many parts of the body. Individuals with trisomy 18 often have slow growth before birth (intrauterine growth retardation) and a low birth weight. Affected individuals may have heart defects and abnormalities of other organs that develop before birth. Other features of trisomy 18 include a small, abnormally shaped head; a small jaw and mouth; and clenched fists with overlapping fingers. Due to the presence of several life-threatening medical problems, many individuals with trisomy 18 die before birth or within their first month. Five to 10 percent of children with this condition live past their first year, and these children often have severe intellectual disability.


[Learn More in MedlinePlus]

Code History

  • FY 2026 - No Change, effective from 10/1/2025 through 9/30/2026
  • FY 2025 - No Change, effective from 10/1/2024 through 9/30/2025
  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.