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ORPHA:1724

Mosaic trisomy 20 syndrome

high confidenceDisorder

Also known as: Mosaic trisomy chromosome 20 · Trisomy 20 mosaicism

Publications

75

27th percentile

Trials

0

Interventional, condition-specific

Researchers

345

Distinct authors in sample

Gene link

—

Readiness

3/6

Stages with a signal

Clinical definition (Orphanet)

Mosaic trisomy 20 is a rare chromosomal anomaly syndrome with a highly variable ranging from normal (in the majority of cases) to a mild, subtle principally characterized by spinal abnormalities (i.e. stenosis, vertebral fusion, and kyphosis), , lifelong constipation, sloped shoulders, skin pigmentation abnormalities (i.e. linear and whorled nevoid hypermelanosis) and significant learning disabilities despite normal intelligence. More severe phenotypes, with patients presenting psychomotor and speech delay, mild facial dysmorphism, cardiac (i.e. ventricular septal defect, dysplastic tricuspid mitral valve) and renal anomalies (e.g. horseshoe kidneys), have also been reported.

How rare: How common this is has not been clearly measured.

Orphanet entry

Cross-references

Joined from Mondo / Orphanet. MeSH labels may enter searches; UMLS / OMIM / NCIT are stored for reference.

Additional Mondo synonyms (1)

Mosaic trisomy type 20

Research stages

Trial readiness signals

Where this condition sits on an open-data research pipeline — not how close a treatment is, and not medical advice. Empty stages often mean “not in these databases under this Mondo ID,” not “impossible.”

3/6 stages with a signal

No specific-condition interventional trial, but broader-category trials exist — discuss eligibility with a clinician.

  1. Gene identifiedNot found

    No GenCC disease–gene assertion in this build

  2. LiteraturePresent

    75 matched papers (9 in last 10 years) Source

  3. Phenotype characterisedPresent

    39 HPO annotations (e.g. Clinodactyly; Dysplastic tricuspid valve; Depigmentation/hyperpigmentation of skin) Source

  4. Animal modelNot found

    No Alliance genotype “model of” associations via Monarch for these Mondo IDs

  5. Orphan designationNot found

    No FDA or EMA orphan-drug designation matched this disease via UMLS or preferred name Source

  6. Interventional trialPartial

    None under the specific name; 22 for broader category trisomy

Biology

Genes and phenotypes

Gene–disease validity from GenCC, plus phenotypes and animal models joined from Monarch Initiative via Mondo ID — not a clinical diagnosis aid.

Do we know what causes it?

Not yet — the cause hasn't been pinned down in GenCC.

No strong gene–disease assertion joined for this Orphanet entity.

Phenotypes (Monarch / HPO)

39

Associated phenotypes · MONDO:0015764

  • Clinodactyly
  • Dysplastic tricuspid valve
  • Depigmentation/hyperpigmentation of skin
  • Chronic constipation
  • Long neck

Showing 5 of 39 — open Monarch for the full list.

Animal models (Monarch / Alliance)

None returned for this Mondo ID. Empty here is not proof that no model organism work exists under another name or gene.

Monarch fetch 2026-07-29

Therapies

Designations, candidates, and chemicals

FDA OOPD and EMA orphan designations, Open Targets clinical candidates, and CTD chemical associations via MyDisease.info. These never change the interventional-trial headline.

Orphan designation (FDA · EMA)

No designation matched this disease via UMLS or preferred name on the FDA OOPD mirror or EMA orphan register. Absence here is not proof that none exists under another wording.

Open Targets candidates

No drugs or clinical candidates returned for this Mondo ID on Open Targets.

CTD chemicals (MyDisease.info)

No CTD chemical associations returned for this Mondo ID.

Literature

Is anyone studying this?

75

75 papers have ever been published on this condition (under this name). For scale, breast cancer has over 700,000. Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=3967) is 59.

75 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 59 (publications denominator n=3967).

9 in the last 10 years · high confidence · 27th percentile (publications denominator)

Phrase hits: 75 · MeSH hits: 0

Open Europe PMC search

Who's working on it?

345

Distinct author names in 75 sampled papers — named people below.

Who's working on it?

No interventional trial matched this name; these authors publish on it in the sampled literature — a practical starting point for contact.

  1. 01
    Hsu LY3 papers · 1991

    Prenatal Diagnosis Laboratory of New York City Medical and Health Research Association of N.Y.C. Inc 10016.

    Papers in Europe PMC
  2. 02
    Chen CP2 papers · 2023

    Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan. cpc_mmh@yahoo.com

    Papers in Europe PMC
  3. 03
    Holzgreve W2 papers · 1989
    Papers in Europe PMC
  4. 04
    Kaffe S2 papers · 1991
    Papers in Europe PMC
  5. 05
    Miny P2 papers · 1989
    Papers in Europe PMC
  6. 06
    Perlis TE2 papers · 1991
    Papers in Europe PMC
  7. 07
    Schwinger E2 papers · 1985
    Papers in Europe PMC
  8. 08
    Spinner NB2 papers · 2020

    Division of Genomic Diagnostics, Department of Pathology and Laboratory Medicines at The Children's Hospital of Philadelphia, Philadelphia, PA, USA.

    Papers in Europe PMC
  9. 09
    Tolmie JL2 papers · 2015

    West of Scotland Clinical Genetics Service, Southern General Hospital, Glasgow DD1 9SY, UK.

    Papers in Europe PMC
  10. 10
    Abuelo DN1 paper · 1986
    Papers in Europe PMC

Clinical research

Is a treatment being tested?

0

interventional trials for this specific condition

No interventional trial testing a treatment matched this specific condition name on ClinicalTrials.gov (observational studies and pan-disease registries are listed separately when present). 22 trials are registered for trisomy, the broader category — shown separately because they may or may not enrol this specific subtype.

Data as of 11 September 2026 · last trial check 11 September 2026

No matched interventional trials. This is true for 77.2% of diseases in the trials denominator (5501 of 7126). Here are the researchers publishing on it.

high confidence · 38.6th percentile (trials denominator)

Recruiting interventional trials

From the matched ClinicalTrials.gov set

No interventional trial testing a treatment was found for this specific condition name on ClinicalTrials.gov.

22 interventional trials matched trisomy, the broader category — listed below. Those studies are not counted in the condition-specific total.

Broader category: trisomy

22

Interventional trials for the parent category, exclusive of NCT IDs already counted above. Eligibility for this subtype is not guaranteed.

Worth raising with a clinician. How we count trials.

Recruiting under the broader category

Other registries (secondary)

Broader net from EU CTIS, ISRCTN, and ICTRP when available — deduped against ClinicalTrials.gov IDs already counted above. Dual-model LLM relevance gates what we keep. These rows are not added to the interventional headline.

raw 0 · after dedupe 0 · already on CT.gov 0 · kept 0 · parent 0 · uncertain 0 · dropped 0 · fetched 2026-07-29

Source notes: ictrp: Error: ICTRP public search unavailable (WHO portal is SPA-only; SOAP needs partnership). Tried: https://apps.who.int/tri

No secondary-registry studies passed dual-model relevance for this condition name (after dedupe).

Where to find support

Condition-specific patient organisations, when Orphanet lists them, are on the disease’s Orphanet page. We also link umbrella groups that support undiagnosed and ultra-rare families.

Orphanet entry for Mosaic trisomy 20 syndrome — check Associations / patient organisations on that page.

India — NPRD

Last verified 2026-07-26

This ORPHAcode is not on our curated NPRD list (direct or Mondo-parent match). That does not decide clinical eligibility; families in India should ask a notified Centre of Excellence about current coverage.

Hand-curated for this project. ORPHAcode mappings are best-effort and may be incomplete or imprecise for umbrella categories. Parent (Mondo) matches mean the policy lists a broader category — confirm eligibility with a Centre of Excellence. Financial entitlements summarised from public policy statements and may change. This is not official government guidance.

How we counted this

Europe PMC query (preferred label + any corrected label + Orphanet and Mondo exact synonyms, stoplisted; unioned with resolved MeSH labels when available). UMLS / OMIM / NCIT cross-references are stored on the overview but are not added to the query string.

"Mosaic trisomy 20 syndrome" OR "Mosaic trisomy chromosome 20" OR "Trisomy 20 mosaicism" OR "Mosaic trisomy type 20"

Run this search on Europe PMC

ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):

"Mosaic trisomy 20 syndrome" OR "Mosaic trisomy chromosome 20" OR "Trisomy 20 mosaicism" OR "Mosaic trisomy type 20"

Study-type breakdown: 0 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.

Parent-category trials query:

"trisomy"

Query health: ok — strategies attempted: phrase; with hits: phrase

Run this search on ClinicalTrials.gov

Confidence reasoning

  • Preferred label is multi-word and distinctive
  • No synonyms dropped by stoplist
  • No label/synonym collisions with other diseases in this corpus

Ingested 2026-07-26T18:02:37.885Z