2026 ICD-10-CM Diagnosis Code Q98.1Klinefelter syndrome, male with more than two X chromosomes

ICD-10-CM Codes›Q00-Q99›Q90-Q99›Q98

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

Q98.1 is a billable ICD-10-CM diagnosis code for klinefelter syndrome, male with more than two X chromosomes. 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
Q98.1
Billable Status
Yes — Valid for Submission
Code Describes
Klinefelter syndrome, male with more than two X chromosomes
Short Description
Klinefelter syndrome, male with more than two X chromosomes
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 CodeQ98.1Klinefelter syndrome, male with more than two X chromosomes

Present on Admission (POA)Billing

Q98.1 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.

  • Klinefelter syndrome
  • Klinefelter's syndrome XXXXY
  • Klinefelter's syndrome XXXY
  • Klinefelter's syndrome, XXYY
  • Klinefelter's syndrome, XY/XXY mosaic
  • Mosaic including XXXXY
  • Sex chromosome mosaicism
  • XXXXY syndrome
  • XXXY 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.

    • Klinefelter's syndrome
      • male with more than two X chromosomes
    • Syndrome
      • XXXXY
    • XXXXY syndrome

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

  • Klinefelter Syndrome

    a form of male hypogonadism, characterized by the presence of an extra x chromosome, small testes, seminiferous tubule dysgenesis, elevated levels of gonadotropins, low serum testosterone, underdeveloped secondary sex characteristics, and male infertility (infertility, male). patients tend to have long legs and a slim, tall stature. gynecomastia is present in many of the patients. the classic form has the karyotype 47,xxy. several karyotype variants include 48,xxyy; 48,xxxy; 49,xxxxy, and mosaic patterns ( 46,xy/47,xxy; 47,xxy/48,xxxy, etc.).

Patient EducationClinical

Klinefelter Syndrome

Klinefelter syndrome (KS) is a genetic condition that happens when a male is born with an extra copy of the X chromosome. KS can affect different stages of physical, language, and social development. It also usually causes infertility.

The full article covers:

  • What is Klinefelter syndrome (KS)?
  • What causes Klinefelter syndrome (KS)?
  • What are the symptoms of Klinefelter syndrome (KS)?
  • How is Klinefelter syndrome (KS) diagnosed?
  • What are the treatments for Klinefelter syndrome (KS)?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert Q98.1 to ICD-9-CMHistory

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

ICD-9-CM
758.7 Klinefelter's syndrome
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 Q98.1Overview

Is Q98.1 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report klinefelter syndrome, male with more than two X chromosomes on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Q98.1 group to?

When klinefelter syndrome, male with more than two X chromosomes 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 Q98.1 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 klinefelter syndrome, male with more than two X chromosomes on inpatient claims.

What is the ICD-9 equivalent of Q98.1?

Under the General Equivalence Mappings, klinefelter syndrome, male with more than two X chromosomes converts to ICD-9-CM 758.7 (Klinefelter's syndrome). 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.