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ORPHA:99803

Haddad syndrome

low confidenceDisorder

Also known as: Congenital central alveolar hypoventilation-Hirschsprung disease syndrome · Ondine-Hirschsprung disease · Ondine-Hirschsprung syndrome

Publications

3,967

Trials

0

Interventional, condition-specific

Researchers

605

Distinct authors in sample

Gene link

PHOX2B

Definitive

Readiness

3/6

Stages with a signal

Clinical definition (Orphanet)

Haddad syndrome is a rare disorder in which central hypoventilation syndrome (CCHS), or Ondine syndrome, occurs concurrently with Hirschsprung disease.

How rare: <1 / 1 000 000 — fewer than one in a million. In a city the size of Kolkata, that might mean on the order of fifteen people.

Orphanet entry

Cross-references

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

Additional Mondo synonyms (3)

congenital central alveolar hypoventilation-Hirschsprung disease syndrome · ondine-Hirschsprung disease · ondine-Hirschsprung syndrome

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 — PHOX2B

  2. LiteraturePresent

    3,967 matched papers (2,596 in last 10 years) Source

  3. Phenotype characterisedPresent

    18 HPO annotations (e.g. Central hypoventilation; Central sleep apnea; Intellectual disability) 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 (PHOX2B).

GenCC classification: Definitive.

Phenotypes (Monarch / HPO)

18

Associated phenotypes · MONDO:0020493

  • Central hypoventilation
  • Central sleep apnea
  • Intellectual disability
  • Seizure
  • Hypotonia

Showing 5 of 18 — 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?

3,967

3,967 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.

3,967 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).

2,596 in the last 10 years · low confidence

Phrase hits: 109 · MeSH hits: 0

Open Europe PMC search

Who's working on it?

605

Distinct author names in 109 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
    Amiel J6 papers · 2014

    Département de Génétique, Unité INSERM U-393, Hôpital Necker-Enfants Malades, 149 rue de Sèvres, 75743 Paris Cedex 15, France.

    Papers in Europe PMC
  2. 02
    Lyonnet S5 papers · 2006
    Papers in Europe PMC
  3. 03
    Munnich A4 papers · 2006
    Papers in Europe PMC
  4. 04
    Trochet D4 papers · 2006

    Unité de Recherches sur les Handicaps Génétiques de l'Enfant, INSERM U-393, and Département de Génétique, Hôpital Necker-Enfants Malades, Paris, France.

    Papers in Europe PMC
  5. 05
    Chen KC3 papers · 2021

    MD Anderson Cancer Centre, University of Texas, Houston, TX, 77030, USA.

    Papers in Europe PMC
  6. 06
    Croaker GD3 papers · 2021

    Royal Alexandra Hospital for Children, Sydney, Australia.

    Papers in Europe PMC
  7. 07
    Goldstein AM3 papers · 2021

    Department of Pediatric Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.

    Papers in Europe PMC
  8. 08
    Heuckeroth RO3 papers · 2023

    Department of Pediatrics, The Children's Hospital of Philadelphia Research Institute, USA; The Perelman School of Medicine at the University of Pennsylvania, Abramson Research Center, 3615 Civic Center Boulevard, Philadelphia, PA 19104, USA. Electronic address: heuckerothr@email.chop.edu.

    Papers in Europe PMC
  9. 09
    Hofstra RM3 papers · 2013
    Papers in Europe PMC
  10. 10
    Kinney HC3 papers · 2010
    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.

low 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 1 · after dedupe 1 · already on CT.gov 0 · kept 0 · parent 0 · uncertain 1 · 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).

Uncertain / not reviewed (1)

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 Haddad 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.

("Haddad syndrome" OR "Congenital central alveolar hypoventilation-Hirschsprung disease syndrome" OR "Ondine-Hirschsprung disease" OR "Ondine-Hirschsprung syndrome") OR ("PHOX2B" OR "PHOX2B syndrome" OR "PHOX2B-related")

Run this search on Europe PMC

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

"Haddad syndrome" OR "Congenital central alveolar hypoventilation-Hirschsprung disease syndrome" OR "Ondine-Hirschsprung disease" OR "Ondine-Hirschsprung syndrome"

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

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 (3967) is implausibly high for prevalence class "<1 / 1 000 000" — treat as possible over-matching, not a measure of research intensity

Ingested 2026-07-27T06:18:43.859Z