Caring for someone with this diagnosis? Eleplan keeps diagnoses, medications, documents and every specialist in one plan.
Start free with EleplanPycnodysostosis
ORPHA:763Disease
Also called Pyknodysostosis
What it is
Pycnodysostosis is a genetic lysosomal disease characterized by osteosclerosis of the skeleton, short stature and brittle bones.
Key facts
- Prevalence
- 1-9 / 1 000 000 (Europe)
- Age of onset
- Adolescent, Adult, Childhood, Infancy
- Inheritance
- 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%
9- Brachydactyly
- Decreased serum insulin-like growth factor 1
- Delayed pneumatization of the mastoid process
- Disproportionate short-limb short stature
- Frontal bossing
- Increased bone mineral density
- Obtuse angle of mandible
- Osteolytic defects of the distal phalanges of the hand
- Persistent open anterior fontanelle
Common30–79%
20- Abnormality of the dentition
- Abnormal nail morphology
- Blue sclerae
- Chronic pain
- Convex nasal ridge
- Decreased response to growth hormone stimulation test
- Delayed cranial suture closure
- Generalized osteosclerosis
- Hypoplasia of the maxilla
- Increased susceptibility to fractures
- Intrauterine growth retardation
- Micrognathia
- Midface retrusion
- Mild conductive hearing impairment
- Obstructive sleep apnea
- Prominent nose
- Proptosis
- Short finger
- Short foot
- Small hand
Sometimes5–29%
24- Abnormality of the clavicle
- Acromelia
- Carious teeth
- Delayed eruption of permanent teeth
- Delayed eruption of primary teeth
- Dental malocclusion
- Enamel hypoplasia
- High palate
and 16 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.