2026 ICD-10-CM Diagnosis Code Q77.4Achondroplasia

ICD-10-CM Codes›Q00-Q99›Q65-Q79›Q77

ICD-10-CM Q77.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q77.4 is a billable ICD-10-CM diagnosis code for achondroplasia. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 564 through 566. The code is exempt from POA reporting. Coders also document this condition as acanthosis nigricans. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Musculoskeletal congenital conditions.

Code Identity

ICD-10-CM Code
Q77.4
Billable Status
Yes — Valid for Submission
Code Describes
Achondroplasia
Short Description
Achondroplasia
Same as the full description in the CMS dataset.
Parent Code
Q77
Osteochondrodysplasia with defects of growth of tubular bones and spine

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ65-Q79Congenital malformations and deformations of the musculoskeletal system
CategoryQ77Osteochondrodysplasia with defects of growth of tubular bones and spine
This CodeQ77.4Achondroplasia

Present on Admission (POA)Billing

Q77.4 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.

  • Acanthosis nigricans
  • Achondrogenesis
  • Achondroplasia
  • Hypochondroplasia
  • Lethal chondrodysplasia with fragmented bone
  • Severe achondroplasia, developmental delay, acanthosis nigricans syndrome
  • Severe combined immunodeficiency with low T- and B-cell numbers
  • Short-limb skeletal dysplasia with severe combined immunodeficiency

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Hypochondroplasia
  • Osteosclerosis congenita

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.

    • Achondroplasia(osteosclerosis congenita)
    • Chondrodysplasia
      • fetalis
    • Chondrogenesis imperfecta
    • Dwarfism
      • achondroplastic
    • Dwarfism
      • hypochondroplastic
    • Hypochondroplasia
    • Osteosclerosis
      • congenita

Clinical ClassificationClinical

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

CCSR MAL008
Musculoskeletal congenital conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Achondroplasia

    an autosomal dominant disorder that is the most frequent form of short-limb dwarfism. affected individuals exhibit short stature caused by rhizomelic shortening of the limbs, characteristic facies with frontal bossing and mid-face hypoplasia, exaggerated lumbar lordosis, limitation of elbow extension, genu varum, and trident hand. (online mendelian inheritance in man, http://www.ncbi.nlm.nih.gov/omim, mim#100800, april 20, 2001)

  • Acanthosis Nigricans

    a circumscribed melanosis consisting of a brown-pigmented, velvety verrucosity or fine papillomatosis appearing in the axillae and other body folds. it occurs in association with endocrine disorders, underlying malignancy, administration of certain drugs, or as in inherited disorder.

  • Achondroplasia

    an autosomal dominant disorder caused by mutation(s) in the fgfr3 gene, encoding fibroblast growth factor receptor 3. the condition is characterized by inappropriate cartilage growth plate differentiation and deficient endochondral growth, manifest clinically with severe rhizomelic short stature, short limbs, characteristic facies with frontal bossing and midface hypoplasia.

  • COMP wt Allele|Cartilage Oligomeric Matrix Protein (Pseudoachondroplasia, Epiphyseal Dysplasia 1, Multiple) Gene|Cartilage Oligomeric Matrix Protein wt Allele|Cartilage Oligomeric Matrix Protein(Pseudoachondroplasia, Epiphyseal Dysplasia 1, Multiple) Gene|EDM1|EPD1|MED|PSACH|Pseudoachondroplasia (Epiphyseal Dysplasia 1, Multiple) Gene|THBS5

    human comp wild-type allele is located in the vicinity of 19p13.1 and is approximately 9 kb in length. this allele, which encodes cartilage oligomeric matrix protein, is involved in cartilage structural integrity. mutation of the gene is associated with pseudoachondroplasia and multiple epiphyseal dysplasia 1.

  • FGFR3 wt Allele|ACH|Achondroplasia, Thanatophoric Dwarfism Gene|CD333|CEK2|FGFR3|Fibroblast Growth Factor Receptor 3 (Achondroplasia, Thanatophoric Dwarfism) Gene|Fibroblast Growth Factor Receptor 3 wt Allele|HSFGFR3EX|JTK4

    human fgfr3 wild-type allele is located in the vicinity of 4p16.3 and is approximately 15 kb in length. this allele, which encodes fibroblast growth factor receptor 3 protein, is involved in mitogenesis, differentiation, and bone development and maintenance. alterations in the gene resulting in defects cause, achondroplasia, crouzon syndrome, thanatophoric dysplasia, coronal synostosis, hypochondroplasia, bladder and cervix cancers.

  • Pseudoachondroplasia

    a rare, autosomal dominant inherited disorder caused by mutations in the comp gene. it is characterized by short stature, short arms and legs, waddling walk, osteoarthritis, and limited range of motion at the elbows and hips.

  • Hypochondroplasia

    an autosomal dominant disorder that is often caused by a defect in fibroblast growth factor receptor 3, and characterized by short stature, micromelia, and a comparatively large head. the features are milder than those seen in achondroplasia.

  • Achondrogenesis

    a rare group of disorders characterized by defective development of bones and cartilage.

  • Type II Achondrogenesis|Achondrogenesis, Type II|Hypochondrogenesis|Langer-Saldino Achondrogenesis

    an autosomal dominant condition caused by mutation(s) in the col2a1 gene, encoding collagen alpha-1(ii) chain. it is the most severe of a spectrum of disorders caused by mutations in the col2a1 gene, characterized by short limbs, small chest and lungs, and abnormal ossification of the spine and pelvis. often, infants die at birth or shortly thereafter.

  • Acanthosis Nigricans

    a melanotic cutaneous lesion that develops in the axilla and other body folds. it may be idiopathic, drug-induced, or it may be associated with the presence of an endocrine disorder or malignancy.

  • Hyperandrogenism, Insulin Resistance, Acanthosis Nigricans Syndrome|HAIR-AN Syndrome

    a condition characterized by hyperandrogenism, insulin resistance, and acanthosis nigricans, typically associated with obesity in teenage girls. it is considered to be a subtype of polycystic ovarian syndrome, but may occur in male individuals. etiology is unclear, but some cases may be associated with mutations affecting the tyrosine kinase domain of the insulin receptor.

  • Insulin Resistant Diabetes Mellitus with Acanthosis Nigricans and Hyperandrogenism|Type A Insulin Resistance Syndrome

    a syndrome of insulin resistance caused by mutation(s) in the insr gene, encoding the insulin receptor. this condition is characterized by a clinical triad of hyperinsulinemia, acanthosis nigricans, and hyperandrogenism without lipodystrophy. this is the least severe of a spectrum of disorders; the other two conditions are rabson-mendenhall syndrome and donohoe syndrome.

Patient EducationClinical

Dwarfism

People with dwarfism have short stature. This means that their height is under 4' 10" as an adult. They are usually of normal intelligence. Dwarfism most often does happen in families where both parents are of average height.

Read the full article at MedlinePlus

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

Convert Q77.4 to ICD-9-CMHistory

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

ICD-9-CM
756.4 Chondrodystrophy
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 Q77.4Overview

Is Q77.4 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report achondroplasia on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Q77.4 group to?

When achondroplasia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 565, 566, with relative weights from 0.7493 to 1.5436 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q77.4 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 achondroplasia on inpatient claims.

What is the ICD-9 equivalent of Q77.4?

Under the General Equivalence Mappings, achondroplasia converts to ICD-9-CM 756.4 (chondrodystrophy). 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.