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Start free with EleplanDistal duplication 18q syndrome
ORPHA:1716Malformation syndrome
Also called Distal trisomy 18q · Telomeric duplication 18q · Trisomy 18qter
What it is
A rare, partial autosomal trisomy characterized by a variable phenotype that includes hypotonia, motor delay, mild to severe intellectual disability, seizures, variable cerebral anomalies, finger/toe syndactyly, fifth finger clinodactyly, strabismus, short neck and dysmorphic facial features.
Key facts
- Prevalence
- 1-9 / 1 000 000 (at birth)
- Age of onset
- Antenatal, Neonatal
- 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
Very common80–99%
17- Abnormal dental morphology
- Abnormal hair pattern
- Anteverted nares
- Carious teeth
- Cognitive impairment
- Cryptorchidism
- Dolichocephaly
- Global developmental delay
- Micrognathia
- Posteriorly rotated ears
- Progressive intervertebral space narrowing
- Prominent nasal bridge
- Round face
- Short neck
- Short nose
- Thickened nuchal skin fold
- Triangular face
Common30–79%
7These 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.
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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