Down syndrome
Enable an AI agent to distinguish suspected from confirmed Down syndrome, record an individual's condition-related state and support needs, and identify evidence-supported actions requiring appropriate clinical oversight and consent.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to distinguish suspected from confirmed Down syndrome, record an individual's condition-related state and support needs, and identify evidence-supported actions requiring appropriate clinical oversight and consent.
Down syndrome is a human chromosomal disorder caused by complete or partial trisomy of chromosome 21, producing a consistent but variable pattern of hypotonia, characteristic dysmorphology, developmental delay, and a raised lifetime risk of specific congenital and acquired diseases.
It can be Reconcile screening, clinical and chromosome evidence while retaining unresolved discrepancies.; Produce an individualized condition summary separating observations, associated diagnoses and unanswered questions.; Identify surveillance gaps against an explicitly selected, dated and age-applicable guideline.; Flag documented loss of skills or new symptoms for appropriate clinical assessment.; Prepare accessible care discussions and support referrals around the person's recorded priorities.; Coordinate genetics review and care transitions with linked evidence, responsible professionals and outstanding actions..
Distinguishing features
Check for diagnostic evidence of additional chromosome 21 material; developmental delay or appearance alone does not establish the condition. [CDC: Down Syndrome](https://www.cdc.gov/birth-defects/about/down-syndrome.html)
Distinguish a prenatal screening result indicating increased probability from a diagnostic result establishing the condition. [CDC: Down Syndrome](https://www.cdc.gov/birth-defects/about/down-syndrome.html)
Distinguish separate-copy trisomy 21, translocation and mosaic forms through chromosome findings rather than outward similarity. [CDC: Down Syndrome](https://www.cdc.gov/birth-defects/about/down-syndrome.html)
Check which chromosome has additional material; trisomy involving another chromosome is not evidence of Down syndrome. [CDC: Down Syndrome](https://www.cdc.gov/birth-defects/about/down-syndrome.html)
Keep recognition of Down syndrome separate from predictions about the individual: prenatal tests cannot establish its full future impact. [CDC: Down Syndrome](https://www.cdc.gov/birth-defects/about/down-syndrome.html)
Scope
+ Diagnostic certainty and evidence for additional chromosome 21 material
+ Cytogenetic form, specimen context and unresolved genetic interpretation
+ Individual developmental, communication and functional profile
+ Down syndrome-specific health surveillance and associated-condition links
+ Changes from personal baseline and resulting assessment needs
+ Condition-related support priorities, accessible participation and care transitions
- The person's identity, worth, personality or presumed decision-making capacity
- Complete models of associated heart disease, thyroid disease, sleep apnea or other diagnoses
- Laboratory assay design and specimen-processing workflows
- General pregnancy management and reproductive decisions
- Detailed educational curricula, therapy protocols and service administration
- Population surveillance, prevalence estimation and general chromosome biology
Characteristics
- Diagnostic standing
- Screening indication; clinically suspected; diagnostically confirmed; unresolved discordance; ruled out Controls whether an agent may describe the condition as established and which clarification remains necessary.
- Cytogenetic interpretation
- Separate-copy trisomy 21; translocation; mosaic; other specialist-interpreted finding; unresolved Preserves the documented genetic explanation without inferring it from appearance.
- Diagnostic evidence
- Linked report, method, specimen, collection date and interpreting clinician Makes diagnostic claims traceable and supports review of conflicting results.
- Reported mosaic cell fraction
- Percentage or abnormal-cell count/total examined, with tissue and method; unknown; not applicable Preserves a laboratory observation without converting it into a whole-person severity score.
- Developmental and adaptive baseline
- Domain-specific observations or instrument scores, with date, context and accommodations Supports individual planning and comparison with subsequent observations.
- Communication access
- Preferred language and expressive/receptive modes, communication aids and required accommodations Allows the agent to obtain and represent the person's own concerns and preferences.
- Associated-condition assessment status
- Per condition: not assessed; suspected; confirmed; assessed absent; historical; unresolved Separates syndrome-associated possibilities from diagnoses actually established in this person.
- Surveillance position
- Per assessment: due; scheduled; completed; deferred; declined; applicability unresolved Connects dated guidance to actionable follow-up without treating missing data as normal results.
- Change from personal baseline
- Stable; gaining skills; new difficulty; loss of established skills; insufficient comparison Prevents new problems from being automatically attributed to an existing Down syndrome diagnosis.
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 31 questions.
Diagnostic grounding Record why Down syndrome is suspected or established and what the available chromosome evidence actually supports.
An agent must distinguish a screening indication from a diagnosis before coordinating condition-specific care.
Recognition and certainty
Separate the reason for investigation from the evidence establishing the condition.
Basis of diagnosis
Record the diagnostic conclusion, its author and supporting report; preserve suspicion when confirmation is unavailable.
- Is the current label based on screening, clinical suspicion or a diagnostic investigation? definition
- Which original report and clinician interpretation support the recorded conclusion? provenance
Chromosome interpretation
Represent the documented form and limits of the genetic evidence.
Genetic form and limits
Preserve the reported chromosome result, sampled tissue and any unresolved mosaicism or rearrangement interpretation.
- What chromosome result, specimen, method and cell counts were reported? measurement
- Does a genetics professional identify unresolved interpretation or a need for family investigations? action
- What conclusions about other tissues or individual functioning does this report leave unsupported? boundary
Individual development and function Represent the person's observed abilities and support needs across development.
The registry label cannot substitute for an individual account of communication, learning, movement and daily functioning.
Developmental profile
Track abilities separately across relevant domains.
Documented abilities
Record strengths, difficulties and developmental progress using dated observations with assessment context.
- What can the person currently do in communication, learning, mobility and daily living, with and without support? measurement
- Who assessed these abilities, using which tools, language and accommodations? provenance
Communication and participation
Connect the developmental profile to accessible interactions and personally meaningful activities.
Effective supports
Record which communication, learning and environmental supports help this individual participate.
- How does the person express preferences, discomfort, agreement and refusal most reliably? measurement
- Which support changes would advance a goal expressed by the person, and how will benefit be evaluated? action
Associated health and surveillance Link individual health findings to Down syndrome-specific review requirements.
Condition-aware monitoring requires both documented results and applicable guidance; a syndrome-associated risk is not an individual diagnosis.
Associated-condition evidence
Track assessed and unresolved health concerns without duplicating their clinical models.
Health assessment coverage
Record assessment status for relevant concerns, including cardiac disease, hearing impairment and obstructive sleep apnea. These are associated with Down syndrome. [CDC: Down Syndrome](https://www.cdc.gov/birth-defects/about/down-syndrome.html)
- Which relevant conditions have been assessed, with what dated results and remaining uncertainty? measurement
- Which findings require a linked condition model or specialist review rather than attribution to Down syndrome alone? boundary
Age-applicable surveillance
Attach surveillance decisions to a specific guideline and the person's age and history.
Surveillance plan
Record applicable monitoring, last completion and follow-up ownership. Pediatric guidance addresses thyroid, hearing, vision, sleep and other concerns across age groups. [AAP: Health Supervision](https://publications.aap.org/pediatrics/article/149/5/e2022057010/186778/Health-Supervision-for-Children-and-Adolescents)
- Which guideline version and age range justify each proposed assessment? provenance
- What is due or unresolved, who will arrange it, and what explains any deferral? action
- Where does pediatric guidance cease to apply, requiring an adult-care source? boundary
Longitudinal change and escalation Distinguish the enduring diagnosis from changes in health, behavior and established abilities.
An agent needs a personal baseline and an explicit review pathway to avoid overlooking new problems.
Baseline comparison
Describe what changed, when and under which circumstances.
New difficulty or skill loss
Record changes in communication, self-care, movement, sleep or engagement as observations requiring interpretation.
- Which previously established ability or usual behavior changed, and over what interval? measurement
- What evidence separates a persistent change from differences in setting, support or observation? provenance
Assessment and response
Connect changes to review without assigning an unsupported explanation.
Change review pathway
Preserve proposed explanations as hypotheses and record clinician-directed evaluation, urgency and follow-up.
- Which possible explanations have been evaluated, and which remain hypotheses? boundary
- What documented clinical criteria determine the urgency and responsible service for this change? action
- What follow-up observation will show improvement, persistence or further deterioration? measurement
Supported decisions and continuity Make condition-related decisions accessible and maintain continuity between genetics, developmental and lifelong health services.
A useful Down syndrome model must connect identified needs to chosen support and accountable follow-up.
Accessible condition decisions
Represent the person's participation in discussions about Down syndrome-related assessment and support.
Preferences and decision support
Record accessible explanations, expressed preferences and decision-specific support rather than deriving decision-making ability from the diagnosis.
- What does the person understand and want regarding the proposed condition-related assessment or support? measurement
- What communication assistance and documented consent or representative authority apply to this specific decision? action
Genetics and care handover
Preserve essential condition knowledge when clinical teams or support settings change.
Continuity requirements
Carry forward the chromosome report, individual baseline, surveillance history, effective accommodations and unresolved genetics questions.
- Which Down syndrome-specific evidence and outstanding assessments must the receiving team acknowledge? action
- Who owns unresolved genetic counseling, surveillance and support actions after the transition? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Free (complete) trisomy 21 from meiotic nondisjunction, about 95% of live-born cases
- Mosaic trisomy 21, with a mixture of trisomic and disomic cell lines
- Robertsonian translocation trisomy 21, usually rob(14;21) or rob(21;21)
- Partial or segmental trisomy 21 (duplication of 21q, especially the 21q22 critical region)
- Isochromosome 21q and other rare rearrangements that yield three copies of 21q
- Which of these kinds and varieties hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Wikidata - Q47715 - Primary item for the condition.
- ICD-10 / ICD-10-CM - Q90, Q90.0, Q90.1, Q90.2, Q90.9 - Q90.0 free trisomy, Q90.1 mosaic, Q90.2 translocation, Q90.9 unspecified.
- ICD-11 MMS - LD40.0 - Down syndrome under chromosomal disorders due to extra chromosomes.
- OMIM - 190685 - Phenotype MIM number.
- Orphanet - ORPHA:870 - Rare-disease catalogue entry.
- MeSH - D004314 - NLM medical subject heading.
- SNOMED CT - 41040004 - Clinical finding concept for Down syndrome.
- MONDO - MONDO:0008608 - Monarch Disease Ontology.
- Disease Ontology - DOID:14250 - Disease Ontology identifier.
- Which of these identifiers and schemes hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- ICD-10 and ICD-11 diagnostic coding (World Health Organization)
- Health Supervision for Children With Down Syndrome clinical report (American Academy of Pediatrics)
- Screening for Fetal Chromosomal Abnormalities, Practice Bulletin No. 226 (American College of Obstetricians and Gynecologists)
- NHS Fetal Anomaly Screening Programme standards for trisomy 21 screening (NHS England / UK National Screening Committee)
- ACMG technical standards and guidelines for noninvasive prenatal screening (American College of Medical Genetics and Genomics)
- UN Convention on the Rights of Persons with Disabilities, as applied to people with Down syndrome (United Nations)
- Which of these standards and regulation hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Prenatal combined screening, cell-free DNA (NIPT), and diagnostic karyotype, FISH or microarray after a high-chance result
- Postnatal confirmation on a blood karyotype when the phenotype is recognised at birth
- Paediatric health-supervision visits that schedule heart, hearing, vision, thyroid, coeliac, sleep-apnoea and cervical-spine checks
- Genetic counselling, including parental karyotypes after a translocation case because of recurrence risk
- Education, disability and social-care eligibility under national special-education and disability-rights law
- Haematology pathways for transient abnormal myelopoiesis in newborns and later leukaemia surveillance
- Which of these real-world use hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Live-birth prevalence (many high-income settings) - about 1 in 600-800 (roughly 1.2-1.7) - per 1000 live births
- Share of live-born cases that are free trisomy 21 - about 90-95 - percent
- Congenital heart disease among live-born infants - 40-50 - percent
- Intellectual functioning (full-scale IQ, highly variable) - about 35-70 in many clinic series - IQ points
- Life expectancy in high-resource settings - about 50-60 - years
- NIPT detection rate for trisomy 21 in singleton pregnancies with adequate fetal fraction - >99 - percent
- Age-related live-birth risk at maternal age 40 - on the order of 1 in 100 - live births
- Which of these typical measurements hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Atrioventricular septal defect and other congenital heart disease, a leading cause of early morbidity
- Duodenal atresia, Hirschsprung disease and other gastrointestinal malformations
- Transient abnormal myelopoiesis in newborns and later myeloid leukaemia of Down syndrome (often GATA1-related)
- Early-onset Alzheimer disease, driven in part by APP triplication on chromosome 21
- Atlantoaxial instability with risk of cervical spinal-cord injury during intubation, contact sport or poorly controlled head movement
- Obstructive sleep apnoea, conductive hearing loss, cataracts and refractive error
- Autoimmune thyroid disease, coeliac disease and increased infection risk
- High rate of miscarriage of trisomy-21 pregnancies; NIPT false positives (vanishing twin, low fetal fraction) if treated as diagnostic
- Which of these failure modes and hazards hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- US advocacy and most American medical style prefer 'Down syndrome' (no possessive); UK and much of the Commonwealth still commonly use 'Down's syndrome' (NHS usage).
- The historical term 'mongolism' is obsolete and offensive in all current medical usage.
- Uptake of prenatal screening and rates of termination after a trisomy-21 diagnosis vary widely (very high in some Nordic programmes; much lower where abortion law, religion or late booking limit access).
- Life expectancy, heart-surgery access and adult-care pathways still differ sharply between high-resource and low-resource health systems.
- Which of these regional variation hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Edwards syndrome (trisomy 18) - Karyotype or CMA shows trisomy 18, not 21; phenotype is usually more growth-restricted, with clenched fists, overlapping fingers and much higher neonatal mortality.
- Patau syndrome (trisomy 13) - Karyotype or CMA shows trisomy 13; midline craniofacial defects, holoprosencephaly and postaxial polydactyly are typical and are not the Down syndrome pattern.
- 21q microduplication (segmental) versus free trisomy 21 - Chromosomal microarray shows a limited 21q gain rather than an extra free chromosome 21 on karyotype.
- Mosaic versus complete trisomy 21 - Mosaicism is established by a mix of trisomic and disomic cells on karyotype or FISH, sometimes requiring a second tissue if blood is normal and the phenotype is strong.
- Congenital hypothyroidism without aneuploidy - Newborn TSH/free T4 can be abnormal in both; chromosome analysis (or equivalent) is what confirms or excludes trisomy 21.
- De novo free trisomy 21 versus inherited Robertsonian translocation - Karyotype shows an extra free 21 versus a derived translocation chromosome; parental karyotypes are required after a translocation case because of recurrence risk.
- Transient abnormal myelopoiesis versus progressive myeloid leukaemia of Down syndrome - TAM is a neonatal, usually GATA1-mutated, often self-limited proliferation; persistence, recurrence or later myeloid leukaemia is a distinct clinical course, not a different chromosome diagnosis.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of Down syndrome this model covers, and on what evidence? provenance
Sources
- Down Syndrome, OMIM #190685 - Genetic identity as trisomy 21, OMIM identifier, critical-region genes, and the main cytogenetic classes.
- Health Supervision for Children With Down Syndrome (Clinical Report) - Clinical surveillance schedule, typical comorbidities, and measurements used in paediatric practice.
- ICD-11 MMS LD40.0 Down syndrome - WHO diagnostic code and placement among chromosomal disorders due to extra chromosomes.
- Facts about Down Syndrome - Live-birth occurrence in the United States and public-health framing of the condition.
- Down syndrome (Q47715) - Cross-walk among Wikidata, ICD, MeSH, Orphanet, OMIM and related identifiers.
What the second pass must settle
- Which existing Vercy world model, if any, already owns Down syndrome and should receive this registry link instead of a separate publication?
- What specialist criteria should govern inclusion of rare partial chromosome 21 duplications and discordant prenatal or tissue-specific findings?
- Which current pediatric and adult guidelines should govern surveillance in each supported jurisdiction, and how should conflicting recommendations be represented?
- Which measures best capture individual development and acquired decline across ages, languages and communication profiles without confusing lifelong differences with new impairment?
- What evidence and specialist pathways should govern suspected regression or dementia, including escalation thresholds and uncertainty about alternative explanations?