2027 ICD-10-CM Diagnosis Code Q99.9Chromosomal abnormality, unspecified
ICD-10-CM Codes›Q00-Q99›Q90-Q99›Q99
- Billable — Valid for Submission
- POA Exempt
- Chronic Condition
Q99.9 is a billable ICD-10-CM diagnosis code for chromosomal abnormality, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 951. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chromosomal abnormalities.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q99.9 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Chromosomal abnormalities, not elsewhere classified (Q90-Q99).
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Alpha-thalassemia intellectual disability syndrome linked to chromosome 16
- Anomaly of chromosome pair 1
- Anomaly of chromosome pair 10
- Anomaly of chromosome pair 11
- Anomaly of chromosome pair 12
- Anomaly of chromosome pair 13
- Anomaly of chromosome pair 14
- Anomaly of chromosome pair 15
- Anomaly of chromosome pair 16
- Anomaly of chromosome pair 17
- Anomaly of chromosome pair 18
- Anomaly of chromosome pair 19
- Anomaly of chromosome pair 2
- Anomaly of chromosome pair 20
- Anomaly of chromosome pair 21
- Anomaly of chromosome pair 22
- Anomaly of chromosome pair 3
- Anomaly of chromosome pair 4
- Anomaly of chromosome pair 5
- Anomaly of chromosome pair 6
- Anomaly of chromosome pair 7
- Anomaly of chromosome pair 8
- Anomaly of chromosome pair 9
- Autoimmune lymphoproliferative syndrome
- Autoimmune lymphoproliferative syndrome due to CTLA4 haploinsufficiency
- Autosomal chromosomal disorder
- Autosomal dominant hereditary disorder
- Autosomal hereditary disorder
- Autosomal recessive hereditary disorder
- Autosomal translocation
- Cardiac arrhythmia associated with genetic disorder
- CFTR-related disorder
- Chromosomal disorder
- Congenital chromosomal disease
- Deletion of part of short arm of chromosome 16
- Dementia due to chromosomal anomaly
- Dementia due to genetic disease
- Dominant autosomal hereditary disorder, complete penetrance
- Dominant autosomal hereditary disorder, incomplete penetrance
- Genetic disease
- Immunodeficiency associated with chromosomal abnormality
- Periodontitis with genetic disorder
- Ulnar mammary syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q99.9: its own notes plus those printed at block Q90-Q99 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- mitochondrial metabolic disorders (E88.4-)
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Q99.9, its category, or a range that includes it.
Excludes1 4
These codes carry an Excludes1 note naming Q99.9: they are not reported together with it, unless the two conditions are unrelated.
- E25 Adrenogenital disorders
- Block Q50-Q56 Congenital malformations of genital organs
- Q56 Indeterminate sex and pseudohermaphroditism
- Z15 Genetic susceptibility to disease
Code First 1
These codes say to code first a condition named in the note, and Q99.9 is one of the conditions named.
- D84.81 Immunodeficiency due to conditions classified elsewhere
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Abnormal, abnormality, abnormalities See Also: Anomaly;
autosomes Q99.9
chromosome, chromosomal Q99.9
Syndrome See Also: Disease;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Chromosome Aberrations
abnormal number or structure of chromosomes. chromosome aberrations may result in chromosome disorders.
Patient EducationClinical
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.
The full article covers:
- What are genetic disorders?
- What causes genetic disorders?
- What are the types of genetic disorders?
- What are the different ways a genetic disorder can be inherited?
- How are genetic disorders diagnosed?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q99.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q99.9Overview
What is the ICD-10 code for chromosomal abnormality, unspecified?
The ICD-10-CM code for chromosomal abnormality, unspecified is Q99.9 (sometimes written as Q999). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q99.9 (Other chromosome abnormalities, not elsewhere classified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report chromosomal abnormality, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q99.9 group to?
When chromosomal abnormality, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 951 (other Factors Influencing Health Status), which carries a relative weight of 0.5574. Higher weights mean higher Medicare reimbursement.
Is Q99.9 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for chromosomal abnormality, unspecified on inpatient claims. The code appears in the Chromosomal abnormalities, not elsewhere classified (Q90-Q99) range of the CMS exempt list.
What is the ICD-9 equivalent of Q99.9?
Under the General Equivalence Mappings, chromosomal abnormality, unspecified converts to ICD-9-CM 758.9 (chromosome anomaly NOS). The mapping is a direct match.
