{"h1":"Rett Syndrome: ICD-11 Definition and Early Childhood Features","faq":[{"a":"Rett syndrome is classified under ICD-11-MMS code LD90.0 as a neurodevelopmental disorder with characteristic regression and hand stereotypies.","q":"What is the ICD-11 code for Rett syndrome?"},{"a":"Most classic cases are caused by pathogenic variants in the MECP2 gene. Atypical presentations may involve CDKL5 or FOXG1.","q":"Which gene is most associated with classic Rett syndrome?"},{"a":"Early development is typically normal until around 6–18 months, after which regression, loss of purposeful hand use and characteristic midline hand stereotypies emerge.","q":"How early can Rett syndrome features appear?"},{"a":"Yes. Because seizures and autonomic dysfunction are common, prompt paediatric neurology referral is warranted alongside multidisciplinary developmental support.","q":"Does Rett syndrome require neurology referral?"}],"lang":"en","slug":"what-is-rett-syndrome-and-what-are-its-icd-11-features-in-early-childhood","title":"What is Rett Syndrome, and its ICD-11 features in early childhood?","entity":{"key":"rett","kind":"condition","name":"Rett Syndrome","slug":"rett-syndrome"},"lenses":[{"kind":"stakeholder","label":"Doctor","value":"doctor"},{"kind":"domain","label":"Context","value":"context"},{"kind":"intent","label":"Definition","value":"definition"},{"kind":"lifecycle","label":"Screen","value":"screen"},{"kind":"route","label":"Special-Education","value":"special-education"},{"kind":"empowerment","label":"Early Clarity","value":"early_clarity"}],"parent":{"key":"conditions","label":"Conditions"},"related":[{"lang":"en","slug":"what-is-the-icd-11-classification-for-rett-syndrome","title":"ICD-11 Classification of Rett Syndrome (LD90.0)"},{"lang":"en","slug":"what-early-indicators-of-rett-syndrome-should-a-paediatrician-watch-for","title":"Early indicators of Rett syndrome for paediatricians"},{"lang":"en","slug":"what-are-the-known-contributing-factors-for-rett-syndrome-in-early-childhood","title":"Known contributing factors for Rett Syndrome"},{"lang":"en","slug":"what-is-rett-syndrome-and-what-does-it-look-like-in-early-childhood","title":"What is Rett Syndrome, and what does it look like in early childhood?"},{"lang":"en","slug":"which-standardised-tools-are-used-to-assess-rett-syndrome-in-early-childhood","title":"Standardised tools for assessing Rett syndrome in early childhood"},{"lang":"en","slug":"what-is-rett-syndrome","title":"What is Rett Syndrome?"}],"summary":"Rett syndrome (ICD-11 LD90.0) is a neurodevelopmental disorder, usually from MECP2 variants and predominantly affecting females, marked by normal early development followed by regression with loss of purposeful hand use and language, stereotypic midline hand movements, gait abnormality and head-growth deceleration. Seizures and autonomic features are common, warranting prompt neurology referral.","answer_md":"*A girl with normal early milestones who then plateaus and loses purposeful hand use — that clinical arc is the signature of Rett syndrome.*\n\n## In short\nRett syndrome (ICD-11 **LD90.0**) is a neurodevelopmental disorder, in most classic cases caused by pathogenic *MECP2* variants, affecting predominantly females. It is characterised by a period of apparently normal early development followed by regression, with loss of acquired purposeful hand skills and spoken language, gait abnormalities, and the emergence of stereotypic midline hand movements. It is a clinically and genetically defined condition — not a therapy-first label.\n\n## The science, briefly\nThe ICD-11 framing reflects the recognised natural history. After largely typical development through roughly 6–18 months, early childhood features include:\n- **Regression** — loss of previously acquired purposeful hand use and expressive language\n- **Hand stereotypies** — characteristic midline wringing, washing, clapping or mouthing movements\n- **Gait and motor abnormalities** — apraxia, truncal ataxia, or loss of ambulation\n- **Deceleration of head growth** (acquired microcephaly in classic presentations)\n- Frequently associated features: breathing irregularities when awake, bruxism, seizures, autonomic dysfunction and disrupted sleep\n\nGenetic confirmation (*MECP2*) supports classic Rett; atypical variants involve *CDKL5* and *FOXG1*. Because seizures and autonomic involvement are common, this warrants prompt **paediatric neurology** referral alongside developmental support.\n\n## The Pinnacle way\nDevelopmental measurement supports care planning; diagnosis requires an appropriately qualified healthcare professional., under qualified clinician care — never from an app or online form. For confirmed cases we coordinate multidisciplinary support spanning [Rett syndrome care](/rett-syndrome), [occupational therapy](https://www.pinnacleblooms.org/best-occupational-therapy-center-india-proven-improvement-rate) for hand function and posture, and a baseline via the [clinician-administered AbilityScore®](/ask/what-is-the-abilityscore-and-how-is-it-calculated).\n\n## Trusted sources\nWHO ICD-11 (LD90.0); WHO ICF functioning framework; consensus diagnostic criteria for Rett syndrome.\n\n**Next step —** For a child showing developmental regression or hand stereotypies, expedite neurology referral and [partner with Pinnacle](/rett-syndrome) for coordinated developmental support.\n\nThis is general information, not a diagnosis — individual assessment and diagnosis require an appropriately qualified healthcare professional.","canonical":"https://pinnacleblooms.org/ask/what-is-rett-syndrome-and-what-are-its-icd-11-features-in-early-childhood","editorial":{"reviewed_at":"2026-06-11T20:12:18.613642+00:00","reviewed_by":null,"developed_by":"SETU Consortium · Pinnacle Blooms Network"},"alternates":[{"href":"https://pinnacleblooms.org/ask/what-is-rett-syndrome-and-what-are-its-icd-11-features-in-early-childhood","lang":"en","indexable":true}],"dimensions":[{"key":"conditions","label":"Conditions"}],"meta_title":"Rett Syndrome (ICD-11 LD90.0): Definition & Features","meta_robots":"index, follow, max-image-preview:large","everyday_tip":"Document the timeline of acquired-then-lost skills precisely — the regression arc is the most diagnostically useful history and guides genetic and neurology referral.","published_at":"2026-06-10T10:42:00.172548+00:00","reading_paths":[{"key":"understand","items":[{"lang":"en","slug":"what-is-rett-syndrome","title":"What is Rett Syndrome?","reason":"Linked from this answer"},{"lang":"en","slug":"what-is-the-icd-11-classification-for-rett-syndrome","title":"ICD-11 Classification of Rett Syndrome (LD90.0)","reason":"Linked from this answer"},{"lang":"en","slug":"what-is-rett-syndrome-and-what-does-it-look-like-in-early-childhood","title":"What is Rett Syndrome, and what does it look like in early childhood?","reason":"Linked from this answer"},{"lang":"en","slug":"what-is-the-snomed-ct-concept-for-rett-syndrome","title":"What is the SNOMED CT concept for Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"how-does-rett-syndrome-affect-a-child-s-daily-life","title":"How Rett Syndrome Affects a Child's Daily Life","reason":"Same topic"},{"lang":"en","slug":"is-rett-syndrome-considered-a-disability","title":"Is Rett Syndrome considered a disability?","reason":"Same topic"},{"lang":"en","slug":"is-rett-syndrome-genetic-or-hereditary","title":"Is Rett Syndrome Genetic or Hereditary?","reason":"Same topic"},{"lang":"en","slug":"what-are-common-myths-about-rett-syndrome","title":"What are common myths about Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"what-are-the-types-or-levels-of-rett-syndrome","title":"Types and Stages of Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"what-causes-rett-syndrome-in-children","title":"What causes Rett syndrome in children?","reason":"Same topic"},{"lang":"en","slug":"what-does-current-research-show-about-early-intervention-outcomes-for-rett-syndrome-in-children-under-7","title":"Early Intervention Outcomes in Rett Syndrome (Under 7)","reason":"Same topic"},{"lang":"en","slug":"what-other-conditions-often-occur-alongside-rett-syndrome","title":"Conditions That Occur Alongside Rett Syndrome","reason":"Same topic"}],"label":"Understand the subject","total":13},{"key":"signs","items":[{"lang":"en","slug":"what-early-indicators-of-rett-syndrome-should-a-paediatrician-watch-for","title":"Early indicators of Rett syndrome for paediatricians","reason":"Linked from this answer"},{"lang":"en","slug":"what-clinical-red-flags-for-rett-syndrome-warrant-referral-in-a-young-child","title":"Rett Syndrome Red Flags Warranting Referral","reason":"Same topic"},{"lang":"en","slug":"when-should-a-doctor-refer-a-child-with-suspected-rett-syndrome-for-developmental-therapy","title":"When to refer suspected Rett syndrome for developmental therapy","reason":"Same topic"},{"lang":"en","slug":"can-rett-syndrome-be-cured","title":"Can Rett Syndrome Be Cured?","reason":"Same topic"},{"lang":"en","slug":"can-rett-syndrome-be-prevented","title":"Can Rett Syndrome Be Prevented?","reason":"Same topic"},{"lang":"en","slug":"do-boys-show-rett-syndrome-differently","title":"Rett Syndrome in Boys","reason":"Same topic"},{"lang":"en","slug":"do-girls-show-rett-syndrome-differently","title":"Do girls show Rett Syndrome differently?","reason":"Same topic"},{"lang":"en","slug":"how-can-a-frontline-health-worker-spot-a-child-with-possible-rett-syndrome-early","title":"Spotting Possible Rett Syndrome Early","reason":"Same topic"},{"lang":"en","slug":"should-i-be-worried-my-child-might-have-rett-syndrome","title":"Should I be worried my child might have Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"what-are-the-early-signs-of-rett-syndrome","title":"Early Signs of Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"what-are-the-early-signs-of-rett-syndrome-in-a-1-year-old-boy","title":"Early signs of Rett syndrome in a 1-year-old boy","reason":"Same topic"},{"lang":"en","slug":"what-are-the-early-signs-of-rett-syndrome-in-a-1-year-old-girl","title":"Early Signs of Rett Syndrome in a 1-Year-Old Girl","reason":"Same topic"}],"label":"Recognise signs & concerns","total":47},{"key":"causes","items":[{"lang":"en","slug":"what-are-the-known-contributing-factors-for-rett-syndrome-in-early-childhood","title":"Known contributing factors for Rett Syndrome","reason":"Linked from this answer"},{"lang":"en","slug":"are-boys-more-likely-to-have-rett-syndrome","title":"Are boys more likely to have Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"are-girls-more-likely-to-have-rett-syndrome","title":"Are girls more likely to have Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"how-does-early-intervention-for-rett-syndrome-advance-un-child-rights-uncrpd-and-the-sdgs","title":"Early Intervention for Rett Syndrome, UNCRPD & the SDGs","reason":"Same topic"},{"lang":"en","slug":"what-causes-rett-syndrome-in-young-children","title":"What Causes Rett Syndrome in Young Children?","reason":"Same topic"},{"lang":"en","slug":"what-is-the-cost-effectiveness-of-early-therapy-for-rett-syndrome-in-young-children","title":"Cost-effectiveness of early therapy for Rett Syndrome in young children","reason":"Same topic"},{"lang":"en","slug":"what-is-the-prevalence-and-public-health-burden-of-rett-syndrome-among-young-children-in-india","title":"Prevalence and Public-Health Burden of Rett Syndrome in India","reason":"Same topic"}],"label":"Explore causes & influences","total":7},{"key":"assess","items":[{"lang":"en","slug":"which-standardised-tools-are-used-to-assess-rett-syndrome-in-early-childhood","title":"Standardised tools for assessing Rett syndrome in early childhood","reason":"Linked from this answer"},{"lang":"en","slug":"what-is-the-recommended-screening-and-diagnostic-pathway-for-rett-syndrome-in-children-under-7","title":"Rett Syndrome Diagnostic Pathway in Children Under 7","reason":"Same topic"},{"lang":"en","slug":"how-does-abilityscore-track-progress-in-a-child-with-rett-syndrome","title":"How AbilityScore Tracks Progress in a Child with Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"how-is-rett-syndrome-assessed-in-a-young-child","title":"How Rett Syndrome Is Assessed in a Young Child","reason":"Same topic"},{"lang":"en","slug":"how-is-rett-syndrome-assessed-in-children-under-7","title":"How Rett Syndrome Is Assessed in Children Under 7","reason":"Same topic"},{"lang":"en","slug":"what-does-an-abilityscore-of-0-100-mean-for-a-child-with-rett-syndrome","title":"What an AbilityScore® of 0–100 means for a child with Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"what-does-an-abilityscore-of-100-200-mean-for-a-child-with-rett-syndrome","title":"What does an AbilityScore of 100–200 mean for a child with Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"what-does-an-abilityscore-of-200-300-mean-for-a-child-with-rett-syndrome","title":"What does an AbilityScore of 200–300 mean for a child with Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"what-does-an-abilityscore-of-300-400-mean-for-a-child-with-rett-syndrome","title":"AbilityScore 300–400 in Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"what-does-an-abilityscore-of-400-500-mean-for-a-child-with-rett-syndrome","title":"What an AbilityScore of 400–500 Means in Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"what-does-an-abilityscore-of-500-600-mean-for-a-child-with-rett-syndrome","title":"What does an AbilityScore of 500–600 mean for a child with Rett Syndrome?","reason":"Same topic"},{"lang":"en","slug":"what-does-an-abilityscore-of-600-700-mean-for-a-child-with-rett-syndrome","title":"What does an AbilityScore of 600–700 mean for a child with Rett Syndrome?","reason":"Same topic"}],"label":"Understand assessment","total":16},{"key":"therapy","items":[{"lang":"en","slug":"as-a-grandparent-or-caregiver-how-can-i-support-a-child-with-rett-syndrome-day-to-day","title":"How Grandparents and Caregivers Can Support a Child with Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"can-a-child-with-rett-syndrome-attend-a-mainstream-school","title":"Can a Child with Rett Syndrome Attend a Mainstream School?","reason":"Same topic"},{"lang":"en","slug":"can-a-child-with-rett-syndrome-attend-a-regular-school","title":"Can a Child with Rett Syndrome Attend a Regular School?","reason":"Same topic"},{"lang":"en","slug":"can-a-child-with-rett-syndrome-grow-up-to-live-independently","title":"Can a Child with Rett Syndrome Live Independently?","reason":"Same topic"},{"lang":"en","slug":"how-can-a-classroom-teacher-help-a-child-with-rett-syndrome-take-part-and-learn","title":"Helping a Child with Rett Syndrome Take Part and Learn","reason":"Same topic"},{"lang":"en","slug":"how-can-a-district-early-intervention-programme-identify-and-support-children-under-7-with-rett-syndrome","title":"Identifying and Supporting Children Under 7 with Rett Syndrome","reason":"Same topic"},{"lang":"en","slug":"how-can-a-teacher-include-and-support-a-young-child-with-rett-syndrome-in-a-mainstream-classroom","title":"How can a teacher include a child with Rett Syndrome in a mainstream classroom?","reason":"Same topic"},{"lang":"en","slug":"how-does-therapy-help-a-child-with-rett-syndrome-make-progress","title":"How does therapy help a child with Rett Syndrome make progress?","reason":"Same topic"},{"lang":"en","slug":"how-is-rett-syndrome-diagnosed-in-a-child","title":"How is Rett Syndrome diagnosed in a child?","reason":"Same topic"},{"lang":"en","slug":"how-is-rett-syndrome-supported-through-therapy","title":"How is Rett Syndrome supported through therapy?","reason":"Same topic"},{"lang":"en","slug":"my-child-with-rett-syndrome-has-an-abilityscore-of-0-100-what-should-we-do-next","title":"Rett Syndrome AbilityScore®: What to Do Next","reason":"Same topic"},{"lang":"en","slug":"my-child-with-rett-syndrome-has-an-abilityscore-of-100-200-what-should-we-do-next","title":"Rett Syndrome with an AbilityScore of 100–200: your next step","reason":"Same topic"}],"label":"Explore therapy & support","total":68},{"key":"home","items":[{"lang":"en","slug":"how-can-i-support-my-child-with-rett-syndrome-at-home","title":"How can I support my child with Rett Syndrome at home?","reason":"Same topic"}],"label":"At home & in everyday life","total":1}],"what_to_watch":"Regression after normal early development: loss of purposeful hand use and spoken language, emergence of midline hand stereotypies, gait apraxia or ataxia, deceleration of head growth, and waking breathing irregularities.","authority_links":[{"url":"https://icd.who.int/","code":"LD90.0","label":"WHO ICD-11 — Rett syndrome (LD90.0)"},{"url":"https://www.who.int/","label":"WHO — neurodevelopmental disorders overview"}],"last_reviewed_at":"2026-06-10T10:42:00.172548+00:00","meta_description":"Rett syndrome (ICD-11 LD90.0): a MECP2-linked neurodevelopmental disorder with regression, hand stereotypies and gait change. Clinician overview and referr","related_materials":[],"related_techniques":[]}