ORPHA:79303
Congenital bile acid synthesis defect type 2
Also known as: BASD2 · Cholestasis with delta(4)-3-oxosteroid 5-beta-reductase deficiency
Query health: suspect — Only one of 2 strategies returned hits (phrase).
Publications
1,005
Trials
0
Interventional, condition-specific
Researchers
353
Distinct authors in sample
Gene link
AKR1D1
Definitive
Readiness
3/6
Stages with a signal
Clinical definition (Orphanet)
bile acid synthesis defect type 2 (BAS defect type 2) is an anomaly of bile acid synthesis characterized by severe and rapidly cholestatic liver disease, and malabsorption of fat and fat-soluble vitamins.
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:0009339
- MeSH:C535443
- OMIM:235555
- UMLS:C1856127
Additional Mondo synonyms (6)
AKR1D1 congenital bile acid synthesis defect · CBAS2 · bile acid synthesis defect, congenital, type 2 · cholestasis with delta(4)-3-oxosteroid 5-beta-reductase deficiency · congenital bile acid synthesis defect caused by mutation in AKR1D1 · congenital bile acid synthesis defect type 2
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.
- Gene identifiedPresent
Definitive — AKR1D1
- LiteraturePresent
1,005 matched papers (728 in last 10 years) Source
- Phenotype characterisedPresent
39 HPO annotations (e.g. Hyperbilirubinemia; Abnormal circulating enzyme concentration or activity; Failure to thrive) Source
- Animal modelNot found
No Alliance genotype “model of” associations via Monarch for these Mondo IDs
- Orphan designationNot found
No FDA or EMA orphan-drug designation matched this disease via UMLS or preferred name Source
- 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 (AKR1D1).
GenCC classification: Definitive.
Phenotypes (Monarch / HPO)
39
Associated phenotypes · MONDO:0009339
- Hyperbilirubinemia
- Abnormal circulating enzyme concentration or activity
- Failure to thrive
- Extramedullary hematopoiesis
- Fat malabsorption
Showing 5 of 39 — 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?
1,005
1,005 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.
1,005 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).
728 in the last 10 years · low confidence
Phrase hits: 38 · MeSH hits: 0
Who's working on it?
353
Distinct author names in 38 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.
- 01Munnich A5 papers · 2012
Départment de Génétique, Hôpital des Enfants Malades, Paris, France.
Papers in Europe PMC - 02Rötig A5 papers · 2012Papers in Europe PMC
- 03Chretien D3 papers · 2008Papers in Europe PMC
- 04Rustin P3 papers · 2001Papers in Europe PMC
- 05Setchell KD3 papers · 2019
Department of Pathology and Laboratory Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, United States.
Papers in Europe PMC - 06Wang JS3 papers · 2019
The Center for Pediatric Liver Diseases, Children's Hospital of Fudan University, Shanghai 201102, China.
Papers in Europe PMC - 07Zhao J3 papers · 2019
Center for Pediatric Liver Diseases, Children's Hospital of Fudan University, Shanghai 201102, China.
Papers in Europe PMC - 08Barile M2 papers · 2022
Department of Biosciences, Biotechnology, and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy. Electronic address: maria.barile@uniba.it.
Papers in Europe PMC - 09Boddaert N2 papers · 2012Papers in Europe PMC
- 10Bonnefont JP2 papers · 2000Papers 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. 1 observational study did — shown below because natural-history and cohort work can be an important step toward a trial.
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.
Broader category congenital bile acid synthesis defect also has no matched interventional trial. See who's working on it — people publishing on this disease are often the practical next contact when no trial is listed.
Broader category: congenital bile acid synthesis defect
0
Interventional trials for the parent category, exclusive of NCT IDs already counted above. Eligibility for this subtype is not guaranteed.
Parent-category matching found a broader label but no interventional trials under it. How we count trials.
Observational and natural-history studies
1 observational study matches this condition. These do not test a treatment and are not counted in the interventional-trial headline, but they are genuine research: natural-history work often defines the endpoints needed for a future rare-disease trial, and families may be able to enroll.
None of the matched observational studies is currently listed as recruiting.
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 Congenital bile acid synthesis defect type 2 — check Associations / patient organisations on that page.
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.
("Congenital bile acid synthesis defect type 2" OR "BASD2" OR "Cholestasis with delta(4)-3-oxosteroid 5-beta-reductase deficiency" OR "AKR1D1 congenital bile acid synthesis defect" OR "CBAS2" OR "bile acid synthesis defect, congenital, type 2" OR "congenital bile acid synthesis defect caused by mutation in AKR1D1") OR (MESH:"Bile acid synthesis defect, congenital, 2") OR ("AKR1D1" OR "AKR1D1 syndrome" OR "AKR1D1-related")MeSH descriptor terms unioned into the query: Bile acid synthesis defect, congenital, 2
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Congenital bile acid synthesis defect type 2" OR "BASD2" OR "Cholestasis with delta(4)-3-oxosteroid 5-beta-reductase deficiency" OR "AKR1D1 congenital bile acid synthesis defect" OR "CBAS2" OR "bile acid synthesis defect, congenital, type 2" OR "congenital bile acid synthesis defect caused by mutation in AKR1D1" OR "Bile acid synthesis defect, congenital, 2"
Study-type breakdown: 0 interventional · 1 observational · 0 expanded access. Only interventional studies enter the trial headline.
Parent-category trials query:
"congenital bile acid synthesis defect"
Query health: suspect — strategies attempted: phrase, mesh; 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 (1005) is extremely high with unknown/missing prevalence — treat as possible over-matching, not proven research intensity
Ingested 2026-07-27T02:14:27.705Z