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Start free with EleplanXq21 microdeletion syndrome
ORPHA:1435Malformation syndrome
Also called Ayazi syndrome · Del(X)(q21) · Monosomy Xq21
What it is
An X-linked retinal dystrophy characterized by choroideremia, causing in affected males progressive nyctalopia and eventual central blindness. Obesity, moderate intellectual disability and congenital mixed (sensorineural and conductive) deafness are also observed. Female carriers show typical retinal changes indicative of the choroideremia carrier state.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Infancy, Neonatal
- Inheritance
- X-linked recessive
- 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%
4- Chorioretinal abnormality
- Chorioretinal degenerationDiagnostic criterion
- Choroideremia
- Sensorineural hearing impairment
Common30–79%
25- Abnormal cochlea morphology
- Abnormality of the Achilles tendon
- Ankle clonus
- Anterior hypopituitarismDiagnostic criterion
- Ataxia
- Bilateral sensorineural hearing impairment
- Conductive hearing impairment
- Decreased response to growth hormone stimulation test
- Delayed skeletal maturation
- Dilatated internal auditory canal
- Gait ataxia
- Global developmental delay
- Growth delay
- Hyperreflexia
- Intellectual disability, mild
- Obesity
- Optic atrophy
- Peripheral visual field loss
- Pituitary hypothyroidism
- Postnatal growth retardation
- Progressive night blindness
- Reduced visual acuity
- Reticular pigmentary degeneration
- Stapes ankylosis
- Visual acuity test abnormality
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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