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ORPHA:93336

Polydactyly of a triphalangeal thumb

medium confidenceDisorder

Also known as: PPD2 · Preaxial polydactyly type 2

Publications

870

83.9th percentile

Trials

0

Interventional, condition-specific

Researchers

285

Distinct authors in sample

Gene link

LMBR1, SHH

Definitive

Readiness

3/6

Stages with a signal

Clinical definition (Orphanet)

Polydactyly of a triphalangeal thumb or PPD2 is a form of preaxial polydactyly of fingers, a limb syndrome, that is characterized by the presence of a usually opposable triphalangeal thumb with or without additional duplication of one or more skeletal components of the thumb. The thumb appearance can differ widely in shape (wedge to rectangular) or it can be deviated in the radio-ulnar plane (clinodactyly). PPD2 is also associated with systemic syndromes, including Holt-Oram syndrome and Fanconi anemia.

How rare: 1-9 / 100 000 — about one to nine people per hundred thousand.

Orphanet entry

Cross-references

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

Additional Mondo synonyms (4)

polydactyly, preaxial type 2 · polydactyly, preaxial type II · preaxial polydactyly type 2 · triphalangeal thumb, type i

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 matched interventional trial; the gene is known and literature exists — preclinical or natural-history work may still be the practical next step.

  1. Gene identifiedPresent

    Definitive — LMBR1, SHH

  2. LiteraturePresent

    870 matched papers (537 in last 10 years) Source

  3. Phenotype characterisedPresent

    9 HPO annotations (e.g. Postaxial hand polydactyly; Duplication of thumb phalanx; Preaxial hand polydactyly) 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 trialNot found

    No matched interventional trial under our ClinicalTrials.gov rules

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?

Yes — we know a specific gene responsible (LMBR1, SHH).

GenCC classification: Definitive.

Phenotypes (Monarch / HPO)

9

Associated phenotypes · MONDO:0008270

  • Postaxial hand polydactyly
  • Duplication of thumb phalanx
  • Preaxial hand polydactyly
  • Preaxial foot polydactyly
  • Syndactyly

Showing 5 of 9 — 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?

870

870 papers have been published on this condition. That is a real research literature — still far smaller than common diseases (breast cancer: over 700,000 papers). Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=3967) is 59.

870 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).

537 in the last 10 years · medium confidence · 83.9th percentile (publications denominator)

Phrase hits: 52 · MeSH hits: 0

Open Europe PMC search

Who's working on it?

285

Distinct author names in 52 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
    Hill RE6 papers · 2017

    MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Rd, Edinburgh EH4 2XU, UK bob.hill@igmm.ed.ac.uk.

    Papers in Europe PMC
  2. 02
    Lettice LA5 papers · 2017

    MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Rd, Edinburgh EH4 2XU, UK.

    Papers in Europe PMC
  3. 03
    Cormier-Daire V3 papers · 2021

    Imagine Institute, Université de Paris, Clinical Genetics, INSERM UMR 1163, Necker Enfants Malades Hospital, 75015 Paris, France.

    Papers in Europe PMC
  4. 04
    Devenney PS3 papers · 2014

    MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Rd, Edinburgh EH4 2XU, UK.

    Papers in Europe PMC
  5. 05
    Bubshait DK2 papers · 2022

    Department of Pediatrics, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.

    Papers in Europe PMC
  6. 06
    De Angelis C2 papers · 2017

    MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom.

    Papers in Europe PMC
  7. 07
    Essafi A2 papers · 2017

    School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, University of Bristol, Bristol, United Kingdom.

    Papers in Europe PMC
  8. 08
    Grimes G2 papers · 2017

    MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom.

    Papers in Europe PMC
  9. 09
    Groza T2 papers · 2016

    Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, Faculty of Medicine University of New South Wales, Darlinghurst, NSW 2010, Australia.

    Papers in Europe PMC
  10. 10
    Hovius SE2 papers · 2008
    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).

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.

medium 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.

See who's working on it — people publishing on this disease are often the practical next contact when no trial is listed.

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 2026-07-30

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 Polydactyly of a triphalangeal thumb — 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.

("Polydactyly of a triphalangeal thumb" OR "Polydactyly of the a triphalangeal thumb" OR "Preaxial polydactyly type 2" OR "polydactyly, preaxial type 2" OR "polydactyly, preaxial type II" OR "triphalangeal thumb, type i") OR ("LMBR1" OR "LMBR1 syndrome" OR "LMBR1-related" OR "SHH syndrome" OR "SHH-related")

Run this search on Europe PMC

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

"Polydactyly of a triphalangeal thumb" OR "Polydactyly of the a triphalangeal thumb" OR "Preaxial polydactyly type 2" OR "polydactyly, preaxial type 2" OR "polydactyly, preaxial type II" OR "triphalangeal thumb, type i"

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

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

Run this search on ClinicalTrials.gov

Synonyms dropped by stoplist: PPD2

Confidence reasoning

  • Preferred label is multi-word and distinctive
  • 1 synonym(s) dropped by stoplist (may under-count)
  • No label/synonym collisions with other diseases in this corpus

Ingested 2026-07-27T04:16:55.071Z