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ORPHA:90026

Primary erythromelalgia

low confidenceDisorder

Also known as: Primary erythermalgia

Publications

3,869

Trials

2

Interventional, condition-specific

Researchers

1,026

Distinct authors in sample

Gene link

SCN9A

Definitive

Readiness

4/6

Stages with a signal

Clinical definition (Orphanet)

Primary erythermalgia is characterized by intermittent attacks of red, warm, painful burning extremities. It spontaneously arises during early childhood and adolescence in the absence of any detectable underlying disorder.

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 (2)

PERYTHM · primary erythromelalgia

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.”

4/6 stages with a signal

An interventional trial matched this condition name on ClinicalTrials.gov — see trials below.

  1. Gene identifiedPresent

    Definitive — SCN9A

  2. LiteraturePresent

    3,869 matched papers (2,611 in last 10 years) Source

  3. Phenotype characterisedPresent

    27 HPO annotations (e.g. Recurrent respiratory infections; Pedal edema; Decreased/absent ankle reflexes) 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 trialPresent

    2 matched on ClinicalTrials.gov

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 (SCN9A).

GenCC classification: Definitive.

Phenotypes (Monarch / HPO)

27

Associated phenotypes · MONDO:0007571

  • Recurrent respiratory infections
  • Pedal edema
  • Decreased/absent ankle reflexes
  • Abnormality of thrombocytes
  • Leukemia

Showing 5 of 27 — 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

2

Drugs / clinical candidates · MONDO_0007571

CTD chemicals (MyDisease.info)

No CTD chemical associations returned for this Mondo ID.

Literature

Is anyone studying this?

3,869

3,869 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.

3,869 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).

2,611 in the last 10 years · low confidence

Phrase hits: 399 · MeSH hits: 0

Open Europe PMC search

Who's working on it?

1,026

Distinct author names in 200 sampled papers — named people below.

Who's working on it?

People publishing on this condition (sampled Europe PMC records). Affiliation is the most recent found in that sample.

  1. 01
    Drenth JP7 papers · 2008

    Department of Medicine, Division of Gastroenterology and Hepatology, University Medical Center St. Radboud, Nijmegen, The Netherlands. JoostPHDrenth@CS.com

    Papers in Europe PMC
  2. 02
    Li J6 papers · 2026

    Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.

    Papers in Europe PMC
  3. 03
    Cox JJ5 papers · 2026

    Wolfson Institute for Biomedical Research, Division of Medicine, University College London, Gower Street, London, WC1E 6BT, UK. j.j.cox@ucl.ac.uk.

    Papers in Europe PMC
  4. 04
    Te Morsche RH5 papers · 2008
    Papers in Europe PMC
  5. 05
    Wood JN5 papers · 2024

    Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London, UK.

    Papers in Europe PMC
  6. 06
    Kurth I4 papers · 2023

    Institute of Human Genetics, Jena University Hospital, 07743 Jena, Germany.

    Papers in Europe PMC
  7. 07
    Waxman SG4 papers · 2018
    Papers in Europe PMC
  8. 08
    Yang Y4 papers · 2009

    Department of Dermatology, Peking University First Hospital, Beijing, China.

    Papers in Europe PMC
  9. 09
    Bertelli M3 papers · 2020

    MAGI'S LAB, Rovereto (TN), Italy; MAGI EUREGIO, Bolzano, Italy; EBTNA-LAB, Rovereto (TN), Italy. matteo.bertelli@assomagi.org.

    Papers in Europe PMC
  10. 10
    Cregg R3 papers · 2014

    Molecular Nociception Group, Wolfson Institute for Biomedical Research, UCL, Gower Street, London WC1E 6BT, UK.

    Papers in Europe PMC

Clinical research

Is a treatment being tested?

2

interventional trials for this specific condition

2 interventional trials matched this specific condition name; none in our sample are currently recruiting. 6 trials are registered for erythromelalgia, the broader category — shown separately because they may or may not enrol this specific subtype.

Data as of 11 September 2026 · last trial check 28 July 2026

2 interventional trials — more than 77.2% of diseases in the trials denominator have none at all (5501 of 7126; this disease is at the 84.5th percentile).

low confidence · 84.5th percentile (trials denominator)

Recruiting interventional trials

From the matched ClinicalTrials.gov set

2 interventional trials matched after quoted-phrase search and title/condition post-filter.

No currently recruiting studies in the matched set. Open the same search on ClinicalTrials.gov.

Broader category: erythromelalgia

6

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 2026-07-30

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 Primary erythromelalgia — 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.

("Primary erythromelalgia" OR "Primary erythermalgia" OR "PERYTHM") OR ("SCN9A" OR "SCN9A syndrome" OR "SCN9A-related")

Run this search on Europe PMC

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

"Primary erythromelalgia" OR "Primary erythermalgia" OR "PERYTHM"

Interventional trials matched via: phrase (mesh = registered under a MeSH descriptor no name phrase would catch; recall-expansion = gene / selected parent terms used only for trials).

Study-type breakdown: 2 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.

Parent-category trials query:

"erythromelalgia"

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
  • Publication count (3869) is extremely high with unknown/missing prevalence — treat as possible over-matching, not proven research intensity

Ingested 2026-07-27T03:30:00.295Z