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ORPHA:99802

Hemimegalencephaly

low confidenceDisorder

Also known as: Unilateral megalencephaly

Publications

2,345

Trials

2

Interventional, condition-specific

Researchers

1,490

Distinct authors in sample

Gene link

—

Readiness

3/6

Stages with a signal

Clinical definition (Orphanet)

Hemimegalencephaly is a rare cerebral characterized by overgrowth of all or part of a cerebral hemisphere, often with ipsilateral severe cortical or dysgenesis, white matter hypertrophy and dilated lateral ventricle, presenting in early infancy with hemiparesis, severe psychomotor retardation and intractable . Hemimegalencephaly may be an isolated finding or associated with other syndromes such as angioosteohypertrophic syndrome, epidermal nevus syndrome and Ito hypomelanosis. Management includes seizure control by antiepileptic medications and early hemispherectomy.

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)

unilateral megalencephaly

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

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

  1. Gene identifiedNot found

    No GenCC disease–gene assertion in this build

  2. LiteraturePresent

    2,345 matched papers (1,384 in last 10 years) Source

  3. Phenotype characterisedPresent

    33 HPO annotations (e.g. Seizure; Ventriculomegaly; EEG with polyspike wave complexes) 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 (1 recruiting in sample)

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)

33

Associated phenotypes · MONDO:0020492

  • Seizure
  • Ventriculomegaly
  • EEG with polyspike wave complexes
  • Hemimegalencephaly
  • Myoclonus

Showing 5 of 33 — 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

1

Drugs / clinical candidates · MONDO_0020492

CTD chemicals (MyDisease.info)

No CTD chemical associations returned for this Mondo ID.

Literature

Is anyone studying this?

2,345

2,345 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.

2,345 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).

1,384 in the last 10 years · low confidence

Phrase hits: 2,345 · MeSH hits: 63

Open Europe PMC search

Who's working on it?

1,490

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
    Chen H7 papers · 2025

    Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.

    Papers in Europe PMC
  2. 02
    Hua C6 papers · 2025

    Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China. worson78@163.com.

    Papers in Europe PMC
  3. 03
    Lin X6 papers · 2025

    Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China. linxiaoxi@126.com.

    Papers in Europe PMC
  4. 04
    Sun B6 papers · 2025

    Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.

    Papers in Europe PMC
  5. 05
    Baldassari S5 papers · 2024

    Inserm, CNRS, APHP, Institut du Cerveau - Paris Brain Institute - ICM, Hôpital de La Pitié Salpêtrière, Sorbonne Université, Paris, France.

    Papers in Europe PMC
  6. 06
    Baulac S5 papers · 2024

    Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, 75013 Paris, France.

    Papers in Europe PMC
  7. 07
    Fallah A5 papers · 2024

    From the The Warren Alpert Medical School of Brown University (J.-S.C.), Providence, RI; Department of Neurosurgery (W.B.H.), University of Colorado Anschutz, Aurora; Department of Neurosurgery (K.J.W., H.W.P., A.F.), University of California Los Angeles; Department of Neurosurgery (H.W.P.), University of Pittsburgh Medical Center, PA; Department of Medicine (C.-H.T.), University of California Los Angeles; Department of Neurosurgery (A.G.W.), Université de Montréal, Quebec, Canada; and Department of Pediatrics (A.F.), University of California Los Angeles. afallah@mednet.ucla.edu.

    Papers in Europe PMC
  8. 08
    Gao W5 papers · 2025

    Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhizaoju Road, Shanghai, 200011, People's Republic of China.

    Papers in Europe PMC
  9. 09
    Anwar T4 papers · 2026

    Neurology, Children's National Hospital, Washington, District of Columbia, USA.

    Papers in Europe PMC
  10. 10
    Kratimenos P4 papers · 2026

    Neonatology, Children's National Hospital, Washington, District of Columbia, USA.

    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; 1 currently recruiting in our sample.

Data as of 11 September 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.

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 Hemimegalencephaly — 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.

"Hemimegalencephaly" OR "Unilateral megalencephaly"

Run this search on Europe PMC

MeSH descriptor terms unioned into the query: Hemimegalencephaly

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

"Hemimegalencephaly" OR "Unilateral megalencephaly"

Interventional trials matched via: both (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.

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

Run this search on ClinicalTrials.gov

Confidence reasoning

  • Preferred label is short or not clearly distinctive
  • No synonyms dropped by stoplist
  • No label/synonym collisions with other diseases in this corpus
  • Publication count (2345) is extremely high with unknown/missing prevalence — treat as possible over-matching, not proven research intensity

Ingested 2026-07-27T06:18:33.784Z