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Q99.2 ICD-10-CM Code: Fragile X chromosome

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term · 1 Excludes2
Risk adjustment
RxHCC V08 category 148

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 884 — ORGANIC DISTURBANCES AND INTELLECTUAL DISABILITY (MDC 19)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for Q99.2 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on Q99.2 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Fragile X syndrome

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from Q90-Q99

Coder workflow for Q99.2

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Official instructions as workflow

  • Excludes2 — not part of Q99.2(1 note)

    Coding workflow: The conditions named in this note are not included in Q99.2. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareE88.4

    See the official tabular notes · Guidelines I.A.12.b

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Fragile X chromosome is a billable ICD-10-CM diagnosis code (Q99.2).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name Q99.2 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 10 Excludes1 notes across 3 chapters: E25 — Adrenogenital disorders (via Q99.-), Q50 — Congenital malformations of ovaries, fallopian tubes and broad ligaments (via Q99.-), Q50-Q56 — Congenital malformations of genital organs (Q50-Q56) (via Q99.-), Q51 — Congenital malformations of uterus and cervix (via Q99.-), Q52 — Other congenital malformations of female genitalia (via Q99.-), Q53 — Undescended and ectopic testicle (via Q99.-), Q54 — Hypospadias (via Q99.-), Q55 — Other congenital malformations of male genital organs (via Q99.-), Q56 — Indeterminate sex and pseudohermaphroditism (via Q99.-), Z15 — Genetic susceptibility to disease (via Q99.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Code First instruction: D84.81 — Immunodeficiency due to conditions classified elsewhere (via Q99.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 1 MS-DRG: DRG 884 (MDC 19).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):MAL009 — Chromosomal abnormalities (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Chromosomal abnormalities).

Q97.9 — Sex chromosome abnormality, female phenotype, unspecified, Q98.0 — Klinefelter syndrome karyotype 47, XXY, Q98.1 — Klinefelter syndrome, male with more than two X chromosomes, Q98.3 — Other male with 46, XX karyotype, Q98.4 — Klinefelter syndrome, unspecified, Q98.5 — Karyotype 47, XYY, Q98.6 — Male with structurally abnormal sex chromosome, Q98.7 — Male with sex chromosome mosaicism, Q98.8 — Other specified sex chromosome abnormalities, male phenotype, Q98.9 — Sex chromosome abnormality, male phenotype, unspecified, Q99.0 — Chimera 46, XX/46, XY, Q99.1 — 46, XX true hermaphrodite, Q99.8 — Other specified chromosome abnormalities, 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, +56 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Fragile, fragility”; these codes share that main term but sit in a different category of the Tabular List.

D69.8 — Other specified hemorrhagic conditions (capillary), L60.3 — Nail dystrophy (nails), L67.8 — Other hair color and hair shaft abnormalities (hair), Q78.0 — Osteogenesis imperfecta (bone, congenital), Q95.5 — Individual with autosomal fragile site (autosomal site)

Contextual Map

Every relationship of Q99.2 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run Q99.2 with these 9 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes (10)

Referenced by Code First instructions

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 19 — Mental Diseases and Disorders[MDC crossing]: “Mental Diseases and Disorders — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Fragile, fragility, X chromosome[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Syndrome, fragile X[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (12)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "Q99.2 — Fragile X chromosome." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/q99.2-fragile-x-chromosome

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Fragile X chromosome

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Q99.2 in its code family, with their registry titles.

View all codes in the Q99 family