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Start free with EleplanAtypical Rett syndrome
ORPHA:3095Disease
Also called Atypical RTT · Rett syndrome variant
What it is
A rare genetic neurological disorder characterized by the presence of two or more of the main criteria for classic Rett syndrome (loss of acquired purposeful hand skills, loss of acquired spoken language, gait abnormalities, stereotypic hand movements), a period of regression followed by recovery or stabilization, and five out of eleven supportive criteria (breathing difficulties, bruxism, impaired sleep pattern, abnormal muscle tone, peripheral vasomotor disturbances, scoliosis/kyphosis, delayed growth, small cold hands and feet, inappropriate laughter or screaming spells, decreased pain sensation, and intense eye communication). Like classic Rett syndrome, it almost exclusively affects girls, while the disease course may be either milder or more severe.
Key facts
- Prevalence
- 1-9 / 100 000
- Age of onset
- Neonatal
- Inheritance
- Autosomal dominant, X-linked dominant
- 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%
16- Abnormality of movement
- Abnormal pattern of respiration
- Agitation
- Autistic behavior
- Developmental regression
- EEG abnormality
- Feeding difficulties
- Functional motor deficit
- Gait disturbance
- Intellectual disability
- Involuntary movements
- Loss of speech
- Reduced eye contact
- Seizure
- Sleep abnormality
- Stereotypical hand wringing
Common30–79%
22- Abnormal muscle tone
- Apraxia
- Dystonia
- Episodic tachypnea
- Functional abnormality of the gastrointestinal tract
- Gait ataxia
- Hand apraxia
- Hypotonia
- Inability to walk
- Limb myoclonus
- Loss of ambulation
- Mutism
- Neonatal seizure
- Reduced social responsiveness
- Restrictive behavior
- Secondary microcephaly
- Severe global developmental delay
- Short foot
- Small hand
- Spasticity
- Sudden episodic apnea
- Tongue thrusting
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.
Genes
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.
Benefit programs to look at
Programs whose eligibility touches the same ICD-10 categories. Eligibility is decided by the administering agency, never by this page.
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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