Caring for someone with this diagnosis? Eleplan keeps diagnoses, medications, documents and every specialist in one plan.
Start free with EleplanSkeletal dysplasia-T-cell immunodeficiency-developmental delay syndrome
ORPHA:508533Disease
Also called EXTL3-related neuro-immuno-skeletal dysplasia syndrome · Neuro-immuno-skeletal dysplasia syndrome due to EXTL3 deficiency
What it is
A rare genetic multiple congenital anomalies/dysmorphic syndrome characterized by the association of developmental delay, variable intellectual disability, skeletal dysplasia, and in many cases T-cell immunodeficiency and other immunologic abnormalities. Skeletal findings include short stature, anomalies of the long bones, hands and feet, and pelvis, platyspondyly, cervical malformation, and pectus excavatum. Dysmorphic facial features, such as coarse face, hypertelorism, and broad nasal tip, may be present. Additional reported manifestations are seizures, hyperreflexia, nystagmus, and muscular hypotonia, as well as multiple liver cysts.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Antenatal, Neonatal
- 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%
4Common30–79%
29- Abnormal facial shape
- Abnormality of limb bone morphology
- Abnormality of the cervical spine
- Abnormality of the ilium
- Abnormal thorax morphology
- Acetabular dysplasia
- Aplasia/hypoplasia involving bones of the extremities
- Brachydactyly
- Broad metacarpals
- Broad phalanges of the hand
- Decreased circulating antibody level
- Decreased lymphocyte proliferation in response to mitogen
- Decreased total T cell count
- Delayed ability to sit
- Disproportionate short stature
- Frontal bossing
- Hypereosinophilia
- Hypoplasia of the odontoid process
- Hyporeflexia
- Hypotonia
- Intellectual disability
- Kyphosis
- Lymphopenia
- Microcephaly
- Narrow greater sciatic notch
- Short metacarpal
- Short nose
- Short phalanx of finger
- Specific learning disability
Sometimes5–29%
62- Abnormal repetitive mannerisms
- Absent speech
- Anteverted nares
- Axial hypotonia
- Broad ischia
- Bulbous nose
- Capillary hemangioma
- Cervical cord compression
and 54 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.