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Start free with Eleplan21q22.11q22.12 microdeletion syndrome
ORPHA:261323Malformation syndrome
Also called Del(21)(q22.11q22.12) · Monosomy 21q22.11q22.12
What it is
A rare, genetic, chromosomal anomaly syndrome resulting from a partial deletion of the long arm of chromosome 21 characterized by pre- and post-natal growth delay, short stature, intellectual disability, developmental delay with severe language impairment, thrombocytopenia, and craniofacial dysmorphism which may include microcephaly, downslanted palpebral fissures, low-set ears, broad nose, thin upper vermillion, and downturned corners of the mouth. Brain MRI abnormalities (such as agenesis of the corpus callosum), behavioral problems and seizures may be associated.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Infancy, Neonatal
- Inheritance
- Not applicable
- 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%
18- Abnormal facial shape
- Absent speech
- Atypical behavior
- Brachydactyly
- Bulbous nose
- Camptodactyly
- Clinodactyly
- Coarse facial features
- Failure to thrive in infancy
- Feeding difficulties in infancy
- Intellectual disability
- Microcephaly
- Postnatal growth retardation
- Seizure
- Severe global developmental delay
- Short stature
- Sleep-wake cycle disturbance
- Small nail
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.
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