ORPHA:457
Harlequin ichthyosis
Also known as: Autosomal congenital ichthyosis, Harlequin type · HI · Ichthyosis congenita, Harlequin type
Query health: suspect — Only one of 2 strategies returned hits (phrase).
Publications
631
86.1th percentile
Trials
0
Interventional, condition-specific
Researchers
1,149
Distinct authors in sample
Gene link
ABCA12
Definitive
Readiness
2/6
Stages with a signal
Clinical definition (Orphanet)
A rare ichthyosis characterized at birth by the presence of large, thick, plate-like shell over the whole body associated with severe ectropion, eclabium, and flattened ears, that later develops into a severe scaling erythroderma. Harlequin ichthyosis is the most severe disorder of this group.
How rare: How common this is has not been clearly measured.
Cross-references
Joined from Mondo / Orphanet. MeSH labels may enter searches; UMLS / OMIM / NCIT are stored for reference.
- MONDO:0009443
- OMIM:242500
- UMLS:C0598226
- NCIT:C98934
Additional Mondo synonyms (9)
ARCI4B · Harlequin Ichthyosis · autosomal recessive congenital ichthyosis type 4B · harlequin ichthyosis · hi · ichthyosis , congenital, autosomal recessive 4b (harlequin) · ichthyosis congenita, Harlequin type · ichthyosis fetalis, Harlequin type · ichthyosis, congenital, autosomal recessive type 4B
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.”
2/6 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.
- Gene identifiedPresent
Definitive — ABCA12
- LiteraturePresent
631 matched papers (331 in last 10 years) Source
- Phenotype characterisedNot checked
Not yet enriched from Monarch / HPO
- Animal modelNot checked
Not yet enriched from Monarch / Alliance
- Orphan designationNot checked
FDA/EMA orphan-drug designation not enriched yet
- 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 (ABCA12).
GenCC classification: Definitive.
Phenotypes (Monarch / HPO)
Not enriched in this build — Monarch phenotype joins were not run for this record.
Animal models (Monarch / Alliance)
Not enriched in this build.
Literature
Is anyone studying this?
631
631 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=5449) is 41.
631 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 41 (publications denominator n=5449).
331 in the last 10 years · medium confidence · 86.1th percentile (publications denominator)
Phrase hits: 631 · MeSH hits: 0
Who's working on it?
1,149
Distinct author names in 200 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.
- 01Fischer J10 papers · 2026
Institute of Human Genetics, Medical Faculty and Medical Center, University of Freiburg, Freiburg, Germany.
Papers in Europe PMC - 02Akiyama M5 papers · 2025
Department of Dermatology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8560, Japan. Electronic address: makiyama@med.nagoya-u.ac.jp.
Papers in Europe PMC - 03Mazereeuw-Hautier J5 papers · 2025
Department of Dermatology, European Reference Network - Skin, University Hospital Center of Toulouse, Toulouse, France.
Papers in Europe PMC - 04Oji V5 papers · 2026
Department of Dermatology, University Hospital of Münster, Münster, Germany.
Papers in Europe PMC - 05Diociaiuti A4 papers · 2024
Dermatology Unit and Genodermatosis Unit, Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
Papers in Europe PMC - 06Guez S4 papers · 2022
Pediatrics Department, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy.
Papers in Europe PMC - 07Medvecz M4 papers · 2025
Department of Dermatology, Venereology and Dermatooncology, Semmelweis University, 1085 Budapest, Hungary.
Papers in Europe PMC - 08Shrestha S4 papers · 2022
MaharajgunjMedical Campus, Institute of Medicine Tribhuvan University Kathmandu Nepal.
Papers in Europe PMC - 09Süßmuth K4 papers · 2026
Klinik für Hautkrankheiten, Universitätsklinik Münster, 48149 Münster, Germany.
Papers in Europe PMC - 10Takeichi T4 papers · 2024
Department of Dermatology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8560, Japan.
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 27 July 2026
No matched interventional trials. This is true for 73% of diseases in the trials denominator (5114 of 7003). Here are the researchers publishing on it.
medium confidence · 36.5th 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.
Where to find support
We do not yet link condition-specific patient organisations. These umbrella groups support undiagnosed and ultra-rare families:
India — NPRD
Last verified 2026-07-26This 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.
"Harlequin ichthyosis" OR "Autosomal congenital ichthyosis, Harlequin type" OR "Ichthyosis congenita, Harlequin type" OR "ARCI4B" OR "autosomal recessive congenital ichthyosis type 4B" OR "ichthyosis , congenital, autosomal recessive 4b (harlequin)" OR "ichthyosis fetalis, Harlequin type" OR "ichthyosis, congenital, autosomal recessive type 4B"
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Harlequin ichthyosis" OR "Autosomal congenital ichthyosis, Harlequin type" OR "Ichthyosis congenita, Harlequin type" OR "ARCI4B" OR "autosomal recessive congenital ichthyosis type 4B" OR "ichthyosis , congenital, autosomal recessive 4b (harlequin)" OR "ichthyosis fetalis, Harlequin type" OR "ichthyosis, congenital, autosomal recessive type 4B" OR "ABCA12"
Recall-expansion terms: ABCA12
Study-type breakdown: 0 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.
Query health: suspect — strategies attempted: phrase, recall-expansion; with hits: phrase
Run this search on ClinicalTrials.gov
Synonyms dropped by stoplist: HI
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 2026-07-26T13:54:07.698Z