What's achondroplasia?
Achondroplasia is the most common form of disproportionate short stature (a skeletal dysplasia). A gain-of-function change in the FGFR3 gene leaves FGFR3 signaling constitutively switched on, which restrains the growth of cartilage and bone (endochondral ossification). The result is short limbs (especially the upper arms and thighs), a relatively large head with frontal bossing, and midface hypoplasia, with normal intelligence and usually a normal lifespan. It is autosomal dominant, and about 80% of cases arise from new (de novo) variants. This entry confirms FGFR3.
| Also indexed as | ORPHA:15, MONDO:0007037 |
|---|---|
| Features mapped | 15 |
| Treatments mapped | 4 |
| Published sources | 14 |
| Last reviewed | 2026-08-04 |
Signs and symptoms
Bowing of the legs
Bowing of the legs (genu varum) is common and can develop as a child begins to walk.
Rhizomelia
Rhizomelia means the parts of the limbs closest to the body — the upper arms and thighs — are the most shortened. It is one of the features seen in achondroplasia.
Genu varum
Bowing of the legs (genu varum) commonly develops in achondroplasia as the long bones grow.
Brain stem compression
When the opening at the base of the skull (the foramen magnum) is narrowed, it can press on the lower brainstem and spinal cord. In achondroplasia this is described as a major complication that can lead to sleep apnea, breathing disorders, problems with the spinal cord, fluid build-up around the brain, and sudden death.
Midface retrusion
The middle of the face is underdeveloped (midface hypoplasia/retrusion).
Macrocephaly
The head is relatively large (macrocephaly), often with a prominent forehead (frontal bossing).
Small foramen magnum
The opening at the base of the skull (foramen magnum) can be narrowed, which in infancy may compress the brainstem and sometimes needs surgical decompression.
Frontal bossing
A prominent, protruding forehead (frontal bossing) is a characteristic facial feature of achondroplasia.
Depressed nasal bridge
Common findings include a depressed nasal bridge.
Obstructive sleep apnea
Obstructive sleep apnea — breathing that is repeatedly blocked during sleep — is one of the medical complications that can occur in achondroplasia.
Central sleep apnea
Central sleep apnea — pauses in breathing during sleep because the brain briefly stops signaling the muscles to breathe — is one of the medical complications that can occur in achondroplasia.
Disproportionate short stature
Achondroplasia is characterized by disproportionate short stature: the trunk is close to average length while the arms and legs, especially the upper segments nearest the body, are notably shorter.
Functional abnormality of the middle ear
Middle ear dysfunction — a problem with how the middle ear drains and works — is one of the medical complications that can occur in achondroplasia.
Short nasal bridge
A low, depressed nasal bridge is part of the characteristic midface appearance in achondroplasia.
Spinal canal stenosis
Spinal stenosis — a narrowing of the canal that holds the spinal cord and nerves — is one of the medical complications that can occur in achondroplasia.
How it is diagnosed
Achondroplasia
Diagnosed using: Genetic testing.
“Genetic testing panels that include FGFR3 and evaluation of short-statured parents can support diagnosis.”
Achondroplasia
Diagnosed using: Ultrasound.
“Prenatally, sonographic features of HCH may be detectable from approximately 20 weeks' gestation.”
Achondroplasia
Diagnosed using: FGFR3 genetic testing.
“Achondroplasia, due to a specific pathogenic variant in FGFR3, is the most common viable skeletal dysplasia and the diagnosis is mostly done in the prenatal period.”
Treatment and management
What the research describes, not a recommendation. Treatment decisions belong with your clinician.
This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.
vosoritide
Vosoritide (brand name VOXZOGO) is a C-type natriuretic peptide analogue and the first targeted therapy approved for achondroplasia. It works by countering the overactive FGFR3 signaling that holds back bone growth.
Used to help with: Achondroplasia.
“Vosoritide activates the NPR-B receptor to inhibit the overactive FGFR3 signaling pathway.”
foramen magnum decompression
Surgery to widen the foramen magnum (decompression) is performed when narrowing at the skull base threatens the brainstem or spinal cord, mainly in infancy.
Used to help with: Achondroplasia.
“Foramen magnum…”
limb lengthening surgery
Limb lengthening is a surgical option that has been used in children and adolescents with achondroplasia, sometimes alongside vosoritide, to add height and improve body proportions.
Used to help with: Achondroplasia.
“…the first clinical description of the combination of precision therapy with limb surgery in a relatively large multicentre cohort of paediatric patients with…”
ventriculoperitoneal shunt
A shunt is a thin tube placed surgically to drain excess fluid from around the brain. In children with achondroplasia who develop progressive fluid build-up (hydrocephalus), a shunt is one way this is managed.
Used to help with: Achondroplasia.
“Pediatric achondroplasia is often associated with conditions requiring neurosurgical intervention, including CSF diversion and multilevel spinal decompression.”
What changes how it shows up
Carrying the genetic change is not the whole story. The factors below are described in the research mapped here as changing whether, or how strongly, the condition appears. They modulate how the genotype is expressed; they do not, on their own, cause or cure it.
FGFR3
Achondroplasia is caused by activating changes in the FGFR3 gene. These changes interfere with the way cartilage turns into bone, which leads to disproportionate short stature.
Described as modulating: Achondroplasia.
“Achondroplasia is the most common genetic skeletal dysplasia, caused by activating mutations in the FGFR3 gene that impair endochondral ossification and result in disproportionate short stature.”
How to read the evidence labels
Where this comes from
This guide is built from 14 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.
Take it further
Printed, source-linked documents built from this condition's graph — ready to bring to an appointment or attach to a coverage request. Every claim carries its published source, the same as this guide.