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What is Rett Syndrome, and what does it look like in early childhood?
Rett Syndrome (ICD-11 LD90.0) is a rare neurodevelopmental condition affecting mostly girls, usually caused by a MECP2 gene change. After typically normal early development, skills slow and are lost — especially purposeful hand use and spoken language, with characteristic repetitive hand movements. Diagnosis is clinical and genetic, formed only at a Pinnacle centre.
In this answer 4 sections
When a baby girl develops beautifully for a few months and then her hands seem to lose their purpose, that change has a name — and an explanation.
In short
Rett Syndrome is a rare neurodevelopmental condition, recognised under ICD-11 as LD90.0, that affects mostly girls and is usually caused by a change in the MECP2 gene. Its hallmark is a period of early development that appears typical, followed by a slowing and then a loss of skills already gained — particularly purposeful use of the hands and spoken language. It is identified by clinicians, not by parents, and early recognition opens the door to supportive therapy and genetic confirmation.
What it can look like in early childhood
Most babies with Rett Syndrome grow and develop as expected for the first 6–18 months. Then a recognisable pattern may emerge:
- A slowing of head growth in the first two years
- Loss of purposeful hand skills that were already there — reaching, grasping, holding
- Repetitive hand movements such as wringing, washing, clapping or mouthing
- Loss of spoken words or babble and reduced social engagement, which may later partly return
- Walking that becomes unsteady, or difficulty starting to walk
- Changes in breathing patterns when awake, and reduced eye-pointing or gaze communication
Because this involves a loss of previously gained skills, any regression at any age deserves prompt medical attention — not a wait-and-watch approach.
The Pinnacle way
Developmental measurement supports care planning; diagnosis requires an appropriately qualified healthcare professional., under qualified clinician care — genetic testing and paediatric neurology confirm Rett Syndrome itself. From there, your child's strengths and support needs are mapped, and occupational therapy helps protect and rebuild everyday hand and self-care skills. Learn more about Rett Syndrome and how families are supported.
Trusted sources
WHO ICD-11 classification of Rett Syndrome; American Academy of Pediatrics guidance on developmental regression; ICF framework for functioning and support.
Next step — If your child has lost skills she once had, speak with a Pinnacle clinician without delay.
This is general information, not a diagnosis — individual assessment and diagnosis require an appropriately qualified healthcare professional.
CONNECT THE ANSWER TO YOUR CHILD’S DAY
Something to notice. Something to discuss.
What to notice
Watch for loss of skills your child once had — especially purposeful hand use, babble or words — together with repetitive hand wringing or washing movements and slowing head growth. Any regression deserves prompt medical attention.
In everyday life
Keep a simple month-by-month note or short videos of your child's milestones. A clear picture of what skills appeared — and any that faded — is one of the most helpful things you can bring to a clinician.
Bring your observations and questions to your child’s professional. Choose activities that suit your child’s comfort, abilities and agreed plan.
Bring your questions to a first visitQuestions families ask
Does Rett Syndrome only affect girls?
It is seen overwhelmingly in girls, because it is usually linked to a change in the MECP2 gene on the X chromosome. It can occur in boys but is far rarer and often presents differently. A clinician and genetic testing confirm the picture.
My baby developed normally and then started losing skills — could it be Rett Syndrome?
A period of typical early development followed by loss of skills, especially purposeful hand use and language, is a recognised pattern. Many conditions can cause regression, so any loss of previously gained skills should be assessed promptly by a paediatrician or paediatric neurologist.
Can therapy help a child with Rett Syndrome?
Yes. While Rett Syndrome itself is genetic, occupational, physical and communication therapies help protect movement, support hand function, build alternative communication and improve everyday participation. Support is most effective when started early.
FOLLOW THE SOURCE
References behind this answer.
- Organisation website · further readingWHO ICD-11: Rett Syndrome (LD90.0)
- Organisation website · further readingAAP HealthyChildren: developmental concerns and regression
- Organisation website · further readingWHO ICF framework for functioning and support
References are supplied with this answer. An organisation homepage offers further reading; it does not establish an independent review of this page.
Content attribution: SETU Consortium · Pinnacle Blooms Network.
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