Caring for someone with this diagnosis? Eleplan keeps diagnoses, medications, documents and every specialist in one plan.
Start free with EleplanAtelosteogenesis type II
ORPHA:56304Malformation syndrome
Also called AO2 · AOII · Atelosteogenesis type 2 · De la Chapelle dysplasia · Neonatal osseous dysplasia type 1
What it is
A rare, lethal perinatal bone dysplasia characterized by limb shortening, normal sized skull with cleft palate, hitchhiker thumbs, distinctive facial dysmorphism and radiographic skeletal features, caused by mutations in the diastrophic dysplasia sulfate transporter gene.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Infancy, Neonatal
- Inheritance
- Autosomal recessive
- Classified as
- Malformation syndrome
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Common30–79%
33- Abnormal facial shape
- Bell-shaped thorax
- Bilateral talipes equinovarus
- Brachydactyly
- Broad metacarpals
- Broad phalanx
- Camptodactyly
- Cleft palate
- Dumbbell-shaped femur
- Equinovarus deformity
- Excessive femoral anteversion
- Genu valgum
- Hitchhiker thumb
- Laryngeal cartilage malformation
- Laryngeal stenosis
- Metatarsus adductus
- Narrow chest
- Pulmonary hypoplasia
- Rhizomelia
- Rhizomelic arm shortening
- Sandal gap
- Short femur
- Short lower limbs
- Short metacarpal
- Short neck
- Short phalanx of finger
- Short ribs
- Thoracic hypoplasia
- Thoracolumbar kyphoscoliosis
- Tibial torsion
- Tracheobronchomalacia
- Ulnar deviation of the hand or of fingers of the hand
- Upper limb undergrowth
Sometimes5–29%
18- Bilateral cleft palate
- Cervical kyphosis
- Elbow flexion contracture
- Epicanthus
- Facial midline hemangioma
- Hypertelorism
- Hypoplastic cervical vertebrae
- Long philtrum
and 10 more in this range
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Gene
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
Powered by Eleplan
A rare diagnosis is just the start. Eleplan keeps the whole care plan in one place.
Diagnoses, medications, documents, appointments, and the whole care team — organized and always in sync, so you are not retelling the same story to every new specialist. With Ellie, your AI care assistant, on top of it. Free to start.