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ORPHA:932Disease
What it is
A rare group of lethal skeletal dysplasias characterized by an endochondral ossification deficiency that leads to dwarfism with extreme micromelia, a small thorax, a prominent abdomen, anasarca and polyhydramnios. There are three types of achondrogenesis that exist and that differ clinically, radiologically, histologically and genetically: achondrogensis type 1a, type 1b and type 2.
Key facts
- Prevalence
- 1-9 / 100 000 (at birth, France)
- Age of onset
- Antenatal, Neonatal
- Inheritance
- Autosomal dominant, Autosomal recessive
- Classified as
- Disease
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
Very common80–99%
18- Abnormal enchondral ossification
- Abnormality of bone mineral density
- Anteverted nares
- Aplasia/Hypoplasia of the lungs
- Flat face
- Frontal bossing
- Hydrops fetalis
- Long philtrum
- Macrocephaly
- Micrognathia
- Micromelia
- Narrow chest
- Severe short stature
- Short neck
- Short nose
- Short thorax
- Skeletal dysplasia
- Thickened nuchal skin fold
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.
Genes reported in subtypes
Orphanet records these genes on 4 more specific entries under this disorder, not on this entry itself:
A well-studied disease is usually split into subtypes, and the gene is curated on whichever one the evidence belongs to. Open a subtype to see which gene goes with it.
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.
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