2026 ICD-10-CM Diagnosis Code Q98.8Other specified sex chromosome abnormalities, male phenotype

ICD-10-CM Codes›Q00-Q99›Q90-Q99›Q98

ICD-10-CM Q98.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q98.8 is a billable ICD-10-CM diagnosis code for other specified sex chromosome abnormalities, male phenotype. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 729 through 730. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Chromosomal abnormalities.

Code Identity

ICD-10-CM Code
Q98.8
Billable Status
Yes — Valid for Submission
Code Describes
Other specified sex chromosome abnormalities, male phenotype
Short Description
Other specified sex chromosome abnormalities, male phenotype
Same as the full description in the CMS dataset.
Parent Code
Q98
Other sex chromosome abnormalities, male phenotype, not elsewhere classified

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ90-Q99Chromosomal abnormalities, not elsewhere classified
CategoryQ98Other sex chromosome abnormalities, male phenotype, not elsewhere classified
This CodeQ98.8Other specified sex chromosome abnormalities, male phenotype

Present on Admission (POA)Billing

Q98.8 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • 48,XYYY syndrome
  • 49,XYYYY syndrome
  • Absence of sex chromosome
  • Distal Xq28 microduplication syndrome
  • Familial infantile gigantism
  • Gigantism
  • Hypersomatotropic gigantism
  • Sex chromosome aneuploidy
  • Sex phenotype-karyotype dissociation syndrome
  • X-linked acrogigantism due to Xq26 microduplication
  • XXYY syndrome

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Abnormal, abnormality, abnormalities
      • chromosome, chromosomal
        • sex
          • male phenotype
            • specified NEC
    • Absence(of) (organ or part) (complete or partial)
      • sex chromosome
        • male phenotype

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MAL009
Chromosomal abnormalities
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Gigantism

    the condition of accelerated and excessive growth in children or adolescents who are exposed to excess human growth hormone before the closure of epiphyses. it is usually caused by somatotroph hyperplasia or a growth hormone-secreting pituitary adenoma. these patients are of abnormally tall stature, more than 3 standard deviations above normal mean height for age.

  • Sotos Syndrome

    congenital or postnatal overgrowth syndrome most often in height and occipitofrontal circumference with variable delayed motor and cognitive development. other associated features include advanced bone age, seizures, neonatal jaundice; hypotonia; and scoliosis. it is also associated with increased risk of developing neoplasms in adulthood. mutations in the nsd1 protein and its haploinsufficiency are associated with the syndrome.

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 Q98.8 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
758.81 Oth cond due to sex chrm
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Q98.8Overview

Is Q98.8 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other specified sex chromosome abnormalities, male phenotype on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Q98.8 group to?

When other specified sex chromosome abnormalities, male phenotype is the principal diagnosis on an inpatient stay, it groups to MS-DRG 729, 730, with relative weights from 0.6720 to 1.0587 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q98.8 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 other specified sex chromosome abnormalities, male phenotype on inpatient claims.

What is the ICD-9 equivalent of Q98.8?

Under the General Equivalence Mappings, other specified sex chromosome abnormalities, male phenotype converts to ICD-9-CM 758.81 (oth cond due to sex chrm). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.