Biliary Atresia

Complex MONDO:0008867 Pathograph 13 Show in embeddings browser Neonatal Cholestasis

Biliary atresia is a rare, progressive fibro-obliterative cholangiopathy of the intra- and extrahepatic bile ducts that presents in the neonatal/perinatal period with conjugated hyperbilirubinemia, pale (acholic) stools, and dark urine. It is the leading cause of neonatal cholestasis requiring surgery and the most common indication for pediatric liver transplantation. The etiology is heterogeneous and incompletely understood: proposed contributors include a perinatal viral trigger, a dysregulated/autoimmune inflammatory response directed at the bile duct epithelium, defective bile duct morphogenesis (particularly in the biliary atresia splenic malformation / laterality subtype), genetic susceptibility, and toxin exposure. These converge on cholangiocyte injury, periductal inflammation and fibrosis, progressive obliteration of the biliary tree, cholestasis, and — without timely restoration of bile flow — biliary cirrhosis, portal hypertension, and end-stage liver disease. First-line treatment is the Kasai hepatoportoenterostomy; most patients ultimately require liver transplantation.

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1
Inheritance
5
Pathophys.
12
Phenotypes
13
Pathograph
4
Genes
8
Medical Actions
3
Subtypes
1
Trials
2
Models
1
Deep Research
🏷

Classifications

Harrison's Part
GASTROINTESTINAL
👪

Inheritance

1
Non-Mendelian / multifactorial HP:0001426
Biliary atresia is overwhelmingly sporadic and non-Mendelian: twin studies show very high discordance (including monozygotic pairs) and familial recurrence is rare, implicating gene-environment, epigenetic, or stochastic contributions on top of genetic susceptibility. The syndromic BASM subtype with biallelic PKD1L1 variants is the exception, suggesting an autosomal recessive contribution in that specific form.
Non-Mendelian inheritance
Show evidence (1 reference)
PMID:32504124 SUPPORT Human Clinical
"97.1% twins were discordant, among 55.9% of which were monozygotic twin sets, indicating that BA may be related to genetic phenotype or penetrance."
High monozygotic-twin discordance argues against simple Mendelian inheritance, supporting a non-Mendelian/multifactorial model.
◆

Subtypes

3
Isolated (non-syndromic) biliary atresia
The most common form (roughly 70-85% of cases), presenting as isolated obliterative cholangiopathy without associated congenital anomalies. Often referred to as the perinatal form when jaundice appears after an initial anicteric period, implicating a postnatal/acquired inflammatory or infectious trigger.
Biliary atresia splenic malformation syndrome
An embryonic/fetal, syndromic form (~10-15% of cases) associated with laterality defects — polysplenia or asplenia, situs inversus/abdominal heterotaxy, a preduodenal portal vein, absent inferior vena cava, intestinal malrotation, and cardiac defects. Implicates disrupted left-right patterning and bile duct morphogenesis during embryogenesis; associated with earlier onset and worse outcome.
Cystic biliary atresia
A less common form in which the obliterated extrahepatic biliary tree contains a cyst; may be detected on prenatal or postnatal ultrasound and must be distinguished from a choledochal cyst, which has a much better prognosis.
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Pathophysiology

5
Cholangiocyte Injury of the Bile Duct Epithelium
The initiating lesion is injury to the cholangiocytes lining the extrahepatic (and later intrahepatic) bile ducts. Candidate insults include perinatal hepatotropic viral infection (cytomegalovirus, reovirus, rotavirus), exposure to a plant/environmental toxin (the isoflavonoid biliatresone, which causes an analogous extrahepatic cholangiopathy in livestock and zebrafish), and defective bile duct morphogenesis. Cholangiocyte apoptosis and loss of epithelial integrity expose ductal antigens and initiate the downstream inflammatory cascade.
extrahepatic cholangiocyte CL:0019020 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves extrahepatic cholangiocyte (CL:0019020). CL:0019020 is a cell type from the Cell Ontology. intrahepatic cholangiocyte CL:0002538 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves intrahepatic cholangiocyte (CL:0002538). CL:0002538 is a cell type from the Cell Ontology.
cholangiocyte apoptotic process GO:1902488 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased cholangiocyte apoptotic process (GO:1902488). GO:1902488 is a biological process from the Gene Ontology. ↑ INCREASED
Animal models
Rhesus rotavirus (RRV) neonatal mouse model Mouse recapitulates Rotavirus replication in cholangiocytes initiates the obstructive cholangiopathy, reproducing the cholangiocyte-injury and duct-obliteration sequence of human biliary atresia.
Biliatresone zebrafish model Zebrafish recapitulates Biliatresone reproduces selective extrahepatic-cholangiocyte injury, modeling the toxin route to the cholangiocyte-injury node.
Downstream
Immune-Mediated Periductal Inflammation Cholangiocyte injury exposes ductal antigens and releases danger signals that trigger the periductal innate and adaptive immune response.
Show evidence (2 references)
PMID:23844248 SUPPORT Model Organism
"The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
The rhesus rotavirus murine model reproduces human BA by infecting neonatal cholangiocytes, supporting a perinatal viral cholangiocyte insult as an initiating mechanism.
PMID:27102575 SUPPORT Model Organism
"Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
The plant toxin biliatresone selectively injures extrahepatic cholangiocytes, demonstrating that a targeted cholangiocyte insult can initiate a BA-like extrahepatic cholangiopathy.
Immune-Mediated Periductal Inflammation
Following the initial cholangiocyte insult, a Th1-polarized (interferon-gamma driven) and Th17-associated inflammatory response targets the bile duct epithelium. Portal tracts are infiltrated by CD4+ and cytotoxic CD8+ T cells, macrophages, and NK cells; a relative deficiency of regulatory T cells is thought to permit an autoimmune-like attack on the duct. This immune-mediated periductal inflammation amplifies and perpetuates the epithelial injury that began the disease.
T-helper 1 cell CL:0000545 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves T-helper 1 cell (CL:0000545). CL:0000545 is a cell type from the Cell Ontology. cytotoxic T cell CL:0000910 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cytotoxic T cell (CL:0000910). CL:0000910 is a cell type from the Cell Ontology. T-helper 17 cell CL:0000899 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves T-helper 17 cell (CL:0000899). CL:0000899 is a cell type from the Cell Ontology. macrophage CL:0000235 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves macrophage (CL:0000235). CL:0000235 is a cell type from the Cell Ontology.
inflammatory response GO:0006954 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology. ↑ INCREASED T cell mediated cytotoxicity GO:0001913 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased T cell mediated cytotoxicity (GO:0001913). GO:0001913 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Portal Mesenchymal Cell Activation Sustained periductal inflammation activates fibrogenic mesenchymal cells in the portal tract.
Show evidence (3 references)
PMID:39131670 SUPPORT Human Clinical
"Patients with BA had decreased peripheral blood Treg frequency and lack of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) upregulation despite a highly activated, effector Treg phenotype."
Human BA patients show a regulatory T-cell deficit, supporting failed immune suppression permitting the autoimmune-like attack on the bile ducts.
PMID:34943969 SUPPORT Model Organism
"Infection of newborn T-bet knockout (KO) pups with RRV resulted in a decreased Th1 inflammatory chemokine/cytokine profile when compared to infected wild-type mice."
Genetic ablation of the Th1 master regulator T-bet blunts the Th1 inflammatory profile, evidencing a Th1-driven mechanism of bile duct injury.
PMID:20234283 SUPPORT Model Organism
"we detected the virus in hepatic macrophages and found that infected macrophages promoted neutrophil chemotaxis by release of Mip2/Cxcl2 in response to RRV."
Rotavirus-targeted hepatic macrophages drive neutrophil chemotaxis, evidencing the innate-immune amplification arm of periductal inflammation.
Portal Mesenchymal Cell Activation
Sustained inflammation activates portal fibroblasts and transdifferentiates hepatic stellate cells into a myofibroblast-like, matrix-secreting phenotype — the organ-specific mesenchymal activation step of the conserved fibrotic response in the biliary atresia portal tract.
hepatic stellate cell CL:0000632 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hepatic stellate cell (CL:0000632). CL:0000632 is a cell type from the Cell Ontology.
hepatic stellate cell activation GO:0035733 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased hepatic stellate cell activation (GO:0035733). GO:0035733 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Fibro-obliteration of the Biliary Tree Activated mesenchymal cells deposit excess extracellular matrix, driving progressive fibro-obliteration of the ducts.
Fibro-obliteration of the Biliary Tree
Activated portal myofibroblasts deposit excess extracellular matrix around and within the injured ducts, producing a fibro-obliterative process that progressively narrows and obliterates the extrahepatic biliary tree and damages the intrahepatic ducts, forming the characteristic fibrous remnant at the porta hepatis. This obliteration is the anatomic substrate that the Kasai portoenterostomy attempts to bypass.
collagen fibril organization GO:0030199 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased collagen fibril organization (GO:0030199). GO:0030199 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Cholestasis and Progression to Biliary Cirrhosis Obliteration of the biliary tree blocks bile flow, producing cholestasis that progresses to biliary cirrhosis and portal hypertension.
Show evidence (1 reference)
PMID:32518681 SUPPORT Human Clinical
"Histopathological findings in liver biopsies include the expansion of the portal tracts, with edematous fibroplasia and bile ductular proliferation, with bile plugs in duct lumen."
Portal-tract fibroplasia and ductular reaction on biopsy evidence the fibro-obliterative remodeling of this node.
Cholestasis and Progression to Biliary Cirrhosis
Obliteration of the biliary tree blocks bile flow, causing cholestasis with accumulation of conjugated bilirubin and bile acids. Retained bile constituents are hepatotoxic and, together with ongoing portal fibrosis, drive progression to biliary cirrhosis, portal hypertension, and ultimately end-stage liver disease. Even after a technically successful Kasai procedure, intrahepatic disease frequently progresses, which is why most patients eventually require liver transplantation.
bile acid secretion GO:0032782 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased bile acid secretion (GO:0032782). GO:0032782 is a biological process from the Gene Ontology. ↓ DECREASED
Show evidence (1 reference)
PMID:32518681 SUPPORT Human Clinical
"Biliary atresia is a progressive fibrosing obstructive cholangiopathy of the intrahepatic and extrahepatic biliary system, resulting in obstruction of bile flow and neonatal jaundice."
Obstruction of bile flow producing neonatal jaundice is the cholestatic consequence modeled by this node, on the path to biliary cirrhosis.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Biliary Atresia Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

12
Cardiovascular 3
Portal hypertension FREQUENT HP:0001409 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Portal hypertension (HP:0001409). HP:0001409 is a phenotype from the Human Phenotype Ontology.
Splenomegaly OCCASIONAL HP:0001744 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Splenomegaly (HP:0001744). HP:0001744 is a phenotype from the Human Phenotype Ontology.
Situs inversus totalis OCCASIONAL HP:0001696 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Situs inversus totalis (HP:0001696). HP:0001696 is a phenotype from the Human Phenotype Ontology.
Digestive 3
Prolonged neonatal jaundice VERY_FREQUENT HP:0006579 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Prolonged neonatal jaundice (HP:0006579). HP:0006579 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34884377 SUPPORT Human Clinical
"Biliary atresia (BA) is an obliterative condition of the biliary tract that presents with persistent jaundice and pale stools typically in the first few weeks of life."
Persistent jaundice in the first weeks of life is the defining presenting feature of biliary atresia.
Hepatomegaly FREQUENT HP:0002240 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hepatomegaly (HP:0002240). HP:0002240 is a phenotype from the Human Phenotype Ontology.
Biliary cirrhosis FREQUENT HP:0002613 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Biliary cirrhosis (HP:0002613). HP:0002613 is a phenotype from the Human Phenotype Ontology.
Genitourinary 1
Dark urine FREQUENT HP:0040319 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dark urine (HP:0040319). HP:0040319 is a phenotype from the Human Phenotype Ontology.
Growth 1
Failure to thrive FREQUENT HP:0001508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Other 4
Conjugated hyperbilirubinemia VERY_FREQUENT HP:0002908 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Conjugated hyperbilirubinemia (HP:0002908). HP:0002908 is a phenotype from the Human Phenotype Ontology.
Acholic stools VERY_FREQUENT HP:0011985 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Acholic stools (HP:0011985). HP:0011985 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34884377 SUPPORT Human Clinical
"Biliary atresia (BA) is an obliterative condition of the biliary tract that presents with persistent jaundice and pale stools typically in the first few weeks of life."
Pale (acholic) stools are part of the defining presenting signature of biliary atresia, reflecting absent bile pigment in the gut.
Polysplenia OCCASIONAL HP:0001748 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Polysplenia (HP:0001748). HP:0001748 is a phenotype from the Human Phenotype Ontology.
Cholangitis FREQUENT HP:0030151 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cholangitis (HP:0030151). HP:0030151 is a phenotype from the Human Phenotype Ontology.
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Genetic Associations

4
GPC1
Gene: GPC1 hgnc:4449 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is GPC1 (hgnc:4449). hgnc:4449 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SUSCEPTIBILITY
Show evidence (1 reference)
PMID:32315284 SUPPORT Human Clinical
"Two GPC1 SNPs in high linkage disequilibrium (LD) showed nominal association with BA susceptibility (PAllele = 0.03 for rs6707262 and PAllele = 0.04 for rs6750380), and were eQTL of GPC1."
The study's own finding is a nominal GPC1 association (and eQTL effect), supporting GPC1 as a susceptibility locus of modest effect.
ADD3
Gene: ADD3 hgnc:245 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is ADD3 (hgnc:245). hgnc:245 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SUSCEPTIBILITY
Show evidence (2 references)
PMID:32315284 SUPPORT Human Clinical
"Three SNPs in ADD3 were significantly associated with BA, and rs17095355 was the top SNP"
ADD3 is the most strongly and reproducibly associated susceptibility locus, with rs17095355 the lead SNP across populations.
PMID:32504124 SUPPORT Human Clinical
"97.1% twins were discordant, among 55.9% of which were monozygotic twin sets, indicating that BA may be related to genetic phenotype or penetrance."
Near-universal twin discordance, mostly in monozygotic pairs, evidences the non-Mendelian, susceptibility-plus-trigger architecture of biliary atresia.
PKD1L1
Gene: PKD1L1 hgnc:18053 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is PKD1L1 (hgnc:18053). hgnc:18053 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SUSCEPTIBILITY
Show evidence (2 references)
PMID:30664273 SUPPORT Human Clinical
"deleterious biallelic variants in polycystic kidney disease 1 like 1 (PKD1L1), a gene associated with ciliary calcium signaling and embryonic laterality determination in fish, mice, and humans."
Whole-exome sequencing of BASM patients identified biallelic PKD1L1 variants, linking a ciliary laterality gene to the syndromic subtype.
PMID:37675454 SUPPORT Model Organism
"These data highlight the essential role of pkd1l1 in normal development and function of the zebrafish biliary system, supporting a role for this gene as a cause of BASM."
Zebrafish pkd1l1 loss-of-function produces biliary defects, functionally validating the human BASM candidate gene.
CFC1
Gene: CFC1 hgnc:18292 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is CFC1 (hgnc:18292). hgnc:18292 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SUSCEPTIBILITY
Show evidence (1 reference)
PMID:18162845 SUPPORT Human Clinical
"These results suggest that heterozygous CFC1 mutation may represent a genetic predisposition to biliary atresia splenic malformation syndrome."
Heterozygous CFC1 variants are proposed as a predisposing factor for the BASM laterality subtype.
💊

Medical Actions

8
Kasai Hepatoportoenterostomy
Action: surgical procedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is surgical procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. Ontology label: Surgical Procedure NCIT:C15329
The first-line surgical treatment: the fibrous biliary remnant at the porta hepatis is excised and a Roux-en-Y jejunal limb is anastomosed to the exposed surface to re-establish bile drainage. Outcome is strongly age-dependent — results are best when performed before ~60 days of life. It is palliative in many patients but can defer or avoid transplantation.
Mechanism Target:
BYPASSES Fibro-obliteration of the Biliary Tree — The portoenterostomy surgically bypasses the obliterated extrahepatic biliary tree, re-establishing bile drainage from the porta hepatis.
Show evidence (1 reference)
PMID:36051179 SUPPORT Human Clinical
"BA is always treated surgically, and performing the surgery before the age of 2 mo greatly increases its effectiveness and extends the time until the need for liver transplantation arises."
Establishes the Kasai portoenterostomy as first-line surgery and its strong age-dependence (best before ~2 months).
Liver Transplantation
Action: liver transplantationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is liver transplantation (NCIT:C15271). NCIT:C15271 is a clinical intervention from the NCI Thesaurus. Ontology label: Liver Transplantation NCIT:C15271
Definitive treatment for patients who fail the Kasai procedure or progress to end-stage liver disease. Biliary atresia is the most common indication for pediatric liver transplantation worldwide.
Show evidence (1 reference)
PMID:42486594 SUPPORT Human Clinical
"It remains the leading indication for liver transplant in children without any disease-modifying medical therapies."
Biliary atresia is the leading indication for pediatric liver transplantation, supporting transplant as the definitive therapy.
Ursodeoxycholic Acid
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: ursodeoxycholic acid CHEBI:9907 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses ursodeoxycholic acid (CHEBI:9907). CHEBI:9907 is a therapeutic agent from Chemical Entities of Biological Interest.
A choleretic bile acid used adjunctively after the Kasai procedure to promote bile flow and reduce cholestatic injury.
Mechanism Target:
MODULATES Cholestasis and Progression to Biliary Cirrhosis — As a choleretic bile acid, UDCA promotes bile flow and shifts the bile-acid pool to less hepatotoxic species, mitigating the cholestatic node.
Prophylactic Antibiotics for Cholangitis
Action: antibiotic therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is antibiotic therapy (NCIT:C15620). NCIT:C15620 is a clinical intervention from the NCI Thesaurus. Ontology label: Antibiotic Therapy NCIT:C15620
Antibiotic prophylaxis is commonly used after portoenterostomy to reduce the frequency of ascending bacterial cholangitis, and acute cholangitis episodes are treated with broad-spectrum antibiotics.
Fat-Soluble Vitamin and Nutritional Support
Action: nutritional supportNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is nutritional support (NCIT:C15433). NCIT:C15433 is a clinical intervention from the NCI Thesaurus. Ontology label: Nutritional Support NCIT:C15433
Cholestasis causes fat malabsorption and deficiency of the fat-soluble vitamins A, D, E, and K; supplementation plus MCT-enriched high-calorie nutrition is a mainstay of supportive care to prevent deficiency and support growth.
Post-Kasai Corticosteroid Therapy
Action: corticosteroid pharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is corticosteroid pharmacotherapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
High-dose corticosteroids after hepatoportoenterostomy have been trialed as an adjuvant to improve bile drainage, but the definitive multicenter START randomized trial found no statistically significant benefit in jaundice clearance and an association with earlier serious adverse events. Their use post-Kasai remains controversial and center-dependent.
Show evidence (1 reference)
PMID:24794368 SUPPORT Human Clinical
"high-dose steroid therapy following surgery did not result in statistically significant treatment differences in bile drainage at 6 months, although a small clinical benefit could not be excluded."
The definitive randomized trial found no significant benefit of post-Kasai steroids, tempering this adjuvant's evidence base.
Maralixibat (IBAT Inhibitor)
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Maralixibat is an oral, minimally-absorbed ileal bile acid transporter (IBAT) inhibitor that lowers hepatic bile acid concentration; it is approved for cholestatic pruritus in Alagille syndrome and is under investigation specifically in biliary atresia after Kasai portoenterostomy.
Mechanism Target:
INHIBITS Cholestasis and Progression to Biliary Cirrhosis — IBAT (ASBT/SLC10A2) inhibition blocks ileal bile-acid reuptake, lowering the hepatic bile-acid pool that drives the cholestatic-injury node.
Show evidence (1 reference)
PMID:32653991 SUPPORT Human Clinical
"IBAT inhibitors may potentially lessen or delay liver damage associated with the hepatotoxicity and cholangiopathy of bile acid accumulation."
Provides the mechanistic rationale for IBAT inhibition (maralixibat) as an anticholestatic strategy in biliary atresia.
N-Acetylcysteine (post-Kasai)
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: N-acetyl-L-cysteine CHEBI:28939 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses N-acetyl-L-cysteine (CHEBI:28939). CHEBI:28939 is a therapeutic agent from Chemical Entities of Biological Interest.
Short-course intravenous N-acetylcysteine (150 mg/kg/day for 7 days starting post-Kasai) was evaluated in a Phase 2 minimax-design trial aiming to normalize total serum bile acids; the primary endpoint was not met, though NAC was well-tolerated. Its mechanistic rationale comes from single-cell RNA-seq showing NAC partially reverses hepatic CD177+ neutrophil immune dysfunction in BA.
Show evidence (1 reference)
PMID:40489761 SUPPORT Human Clinical
"Although the primary endpoint was not met, NAC therapy was generally well-tolerated."
A Phase 2 trial of post-Kasai NAC did not meet its bile-acid endpoint but established tolerability, tempering the evidence for this adjuvant.
🌍

Environmental Factors

3
Perinatal hepatotropic viral infection
viral infection ECTO:3000001 Environmental Conditions, Treatments and Exposures Ontology (ECTO) Relation: this environmental factor is this exposure This environmental factor is viral infection, annotated with exposure to virus (ECTO:3000001). ECTO:3000001 is an exposure from the Environmental Conditions, Treatments and Exposures Ontology.
Perinatal infection with a hepatotropic virus (cytomegalovirus, reovirus, or rotavirus) is a leading candidate trigger for the cholangiocyte injury and subsequent immune response, consistent with the seasonal clustering reported in some cohorts and with rotavirus induction of an experimental biliary atresia phenotype in newborn mice.
Show evidence (1 reference)
PMID:23844248 SUPPORT Model Organism
"The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
Rotavirus infection of neonatal mice recapitulates human BA, supporting a perinatal viral trigger for the isolated form.
Mechanism Target:
TRIGGERS Cholangiocyte Injury of the Bile Duct Epithelium — Perinatal hepatotropic viral infection of cholangiocytes is a candidate initiating insult of the disease chain.
Show evidence (1 reference)
PMID:23844248 SUPPORT Model Organism
"The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
Rotavirus infection of neonatal cholangiocytes initiates the obstructive cholangiopathy, acting on the cholangiocyte-injury node.
Biliatresone toxin exposure
biliatresone toxin exposure ECTO:0000537 Environmental Conditions, Treatments and Exposures Ontology (ECTO) Relation: this environmental factor is this exposure This environmental factor is biliatresone toxin exposure, annotated with exposure to toxin (ECTO:0000537). ECTO:0000537 is an exposure from the Environmental Conditions, Treatments and Exposures Ontology.
Biliatresone, an isoflavonoid isolated from Dysphania plants, causes an extrahepatic cholangiopathy resembling biliary atresia in livestock and in zebrafish/organoid models, providing proof of principle that an environmental toxin can selectively injure the extrahepatic biliary epithelium.
Show evidence (2 references)
PMID:27102575 SUPPORT Model Organism
"Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
Biliatresone's selective extrahepatic-cholangiocyte toxicity establishes that an environmental toxin can produce a BA-like lesion.
PMID:38578745 SUPPORT Model Organism
"It likely results from a prenatal environmental exposure that spares the mother and affects the fetus."
Low-dose prenatal biliatresone exposure in pregnant mice supports an in-utero environmental "hit" that affects the fetus without overt maternal illness.
Mechanism Target:
TRIGGERS Cholangiocyte Injury of the Bile Duct Epithelium — The electrophilic toxin biliatresone selectively injures extrahepatic cholangiocytes, acting directly on the initiating injury node.
Show evidence (1 reference)
PMID:27102575 SUPPORT Model Organism
"Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
Biliatresone's selective extrahepatic-cholangiocyte toxicity is the toxin route to the cholangiocyte-injury node.
Prenatal maternal infection
Population-based case-control data associate maternal intestinal and genitourinary tract infections during pregnancy — particularly in the third trimester — with an increased risk of biliary atresia in offspring, consistent with an in-utero inflammatory contribution to pathogenesis.
Show evidence (1 reference)
PMID:38170523 SUPPORT Human Clinical
"Results of this case-control study indicate an association between prenatal intestinal infection and genitourinary tract infection in mothers and BA occurrence in their offspring."
A large Taiwanese case-control study links prenatal maternal gut and genitourinary infection to offspring biliary atresia risk.
Mechanism Target:
PREDISPOSES Cholangiocyte Injury of the Bile Duct Epithelium — Prenatal maternal infection is an epidemiologic risk factor thought to act indirectly (e.g. via maternal-fetal inflammation/dysbiosis) to predispose the fetal biliary epithelium to injury.
Show evidence (1 reference)
PMID:38170523 SUPPORT Human Clinical
"Results of this case-control study indicate an association between prenatal intestinal infection and genitourinary tract infection in mothers and BA occurrence in their offspring."
Population-scale case-control evidence that maternal prenatal infection predisposes offspring to biliary atresia.
🔬

Biochemical Markers

4
Elevated conjugated (direct) bilirubin (Elevated)
Context: Increased serum conjugated/direct bilirubin is the defining biochemical abnormality; a direct bilirubin above ~1.0 mg/dL (or >20% of total) in an infant warrants immediate evaluation for biliary atresia.
Elevated gamma-glutamyltransferase (GGT) (Elevated)
Context: Serum GGT is characteristically high in biliary atresia, in contrast to the low-GGT cholestases (e.g. certain PFIC subtypes), helping to narrow the differential.
Elevated circulating hepatic transaminases (Elevated)
Context: Mild to moderate elevation of ALT and AST reflecting hepatocellular injury accompanying the cholestasis.
Elevated serum matrix metalloproteinase-7 (MMP7) (Elevated)
Context: Serum MMP7, secreted by injured extrahepatic cholangiocytes and involved in extracellular-matrix remodeling, is an emerging diagnostic biomarker that is elevated in biliary atresia and helps discriminate it from other causes of neonatal cholestasis.
🔬

Diagnosis

4
Abdominal ultrasonography (triangular cord sign)
First-line imaging. The "triangular cord" sign — a triangular/tubular echogenic density cranial to the portal vein bifurcation representing the fibrotic biliary remnant — together with an absent, atretic, or non-contractile gallbladder is highly specific for biliary atresia.
abdominal ultrasonography NCIT:C17230 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:9396524 SUPPORT Human Clinical
"Although 17 of 20 ultrasonographic examinations from infants who had BA denoted TC, 43 ultrasonographic examinations from infants with either neonatal hepatitis (NH) or other causes of cholestasis denoted no TC, showing a diagnostic accuracy of 95% with 85% sensitivity and 100% specificity."
The triangular cord sign on ultrasound is highly specific for biliary atresia in the workup of infantile cholestasis.
Hepatobiliary scintigraphy (HIDA)
Technetium-99m HIDA/DISIDA scintigraphy is highly sensitive but poorly specific: absence of tracer excretion into the gut occurs in biliary atresia but also in other cholestases, whereas demonstrated gut excretion effectively excludes it.
Intraoperative cholangiography
The definitive confirmatory test, demonstrating non-patency of the extrahepatic biliary tree; performed at exploratory laparotomy, typically immediately before proceeding to the Kasai portoenterostomy.
intraoperative cholangiography NCIT:C61508 NCI Thesaurus (NCIT)
Infant stool color card screening
A parent-administered population screening tool comparing neonatal stool color to a reference card during the first month of life. National programs (e.g. Taiwan) using it achieve earlier Kasai surgery and improved transplant-free survival.
Show evidence (1 reference)
PMID:27015203 SUPPORT Human Clinical
"Since 2004, Taiwan has implemented a national screening program that uses an infant stool color card (SCC) for the early detection of BA."
Stool color card screening is a validated national program for early detection of biliary atresia.
📊

Prevalence

1
South Korea (nationwide birth cohort)
Birth Prevalence 10.6 per 100,000 1–9 per 10,000
1.06 cases per 10,000 live births in Korea. Incidence is markedly higher in East Asia (Taiwan/Japan) than in Europe (~5-25 per 100,000). A female predominance is reported (adjusted prevalence ratio 1.68, 95% CI 1.33-2.12).
Show evidence (2 references)
PMID:28244293 SUPPORT Human Clinical
"The overall incidence of BA was 1.06 cases per 10,000 live births."
National cohort birth prevalence/incidence figure for biliary atresia in an East-Asian population.
PMID:35364097 SUPPORT Human Clinical
"Biliary atresia was positively associated with female sex (adjusted PR, 1.68; 95% CI, 1.33-2.12)"
Documents the female predominance of biliary atresia birth prevalence.
🔬

Clinical Trials

1
NCT04524390 PHASE_II ACTIVE_NOT_RECRUITING
Randomized, double-blind, placebo-controlled Phase 2 study of the IBAT inhibitor maralixibat in infants with biliary atresia after hepatoportoenterostomy (Breakthrough Therapy designation for biliary atresia).
Show evidence (1 reference)
clinicaltrials:NCT04524390 SUPPORT Human Clinical
"A study to evaluate the efficacy and safety of maralixibat in infants with Biliary Atresia (BA) after Hepatoportoenterostomy (HPE, also known as the Kasai procedure)."
Registers the Phase 2 maralixibat post-Kasai trial referenced by the maralixibat treatment entry.
🐁

Animal Models

2
Rhesus rotavirus (RRV) neonatal mouse model
The canonical experimental model of biliary atresia: infection of newborn mice with rhesus rotavirus produces an obstructive extrahepatic cholangiopathy that mirrors the human disease, with cholangiocyte infection, periductal inflammation, and progressive duct obliteration.
Species
Mouse
Genotype
Wild-type BALB/c neonate infected with rhesus rotavirus
Publication
PMID:23844248
Pathograph links
Cholangiocyte Injury of the Bile Duct Epithelium recapitulates fidelity: moderate Rotavirus replication in cholangiocytes initiates the obstructive cholangiopathy, reproducing the cholangiocyte-injury and duct-obliteration sequence of human biliary atresia.
Limitations: The model is driven by a single defined virus in an inbred neonatal mouse and is time-window restricted; it may not capture the etiologic heterogeneity or the developmental (BASM) forms of human disease.
Show evidence (1 reference)
PMID:23844248 SUPPORT Model Organism
"The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
Establishes the RRV neonatal-mouse model as recapitulating the human cholangiocyte-injury/obstruction mechanism.
Biliatresone zebrafish model
Exposure of zebrafish larvae to the plant toxin biliatresone selectively injures the extrahepatic biliary epithelium, providing a toxin-driven model of the extrahepatic cholangiopathy of biliary atresia.
Species
Zebrafish
Genotype
Wild-type larvae exposed to the isoflavonoid toxin biliatresone
Publication
PMID:27102575
Pathograph links
Cholangiocyte Injury of the Bile Duct Epithelium recapitulates fidelity: moderate Biliatresone reproduces selective extrahepatic-cholangiocyte injury, modeling the toxin route to the cholangiocyte-injury node.
Limitations: Zebrafish biliary anatomy differs from the human extrahepatic tree, and the specific human relevance of biliatresone exposure remains unproven; the model captures the injury mechanism rather than human etiology.
Show evidence (1 reference)
PMID:27102575 SUPPORT Model Organism
"Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
Demonstrates selective extrahepatic-cholangiocyte toxicity, grounding the toxin model of the injury node.
{ }

Source YAML

click to show 
name: Biliary Atresia
creation_date: "2026-08-12T00:00:00Z"
category: Complex
disease_term:
  preferred_term: biliary atresia
  term:
    id: MONDO:0008867
    label: biliary atresia
description: >-
  Biliary atresia is a rare, progressive fibro-obliterative cholangiopathy of the
  intra- and extrahepatic bile ducts that presents in the neonatal/perinatal period
  with conjugated hyperbilirubinemia, pale (acholic) stools, and dark urine. It is
  the leading cause of neonatal cholestasis requiring surgery and the most common
  indication for pediatric liver transplantation. The etiology is heterogeneous and
  incompletely understood: proposed contributors include a perinatal viral trigger,
  a dysregulated/autoimmune inflammatory response directed at the bile duct
  epithelium, defective bile duct morphogenesis (particularly in the biliary atresia
  splenic malformation / laterality subtype), genetic susceptibility, and toxin
  exposure. These converge on cholangiocyte injury, periductal inflammation and
  fibrosis, progressive obliteration of the biliary tree, cholestasis, and — without
  timely restoration of bile flow — biliary cirrhosis, portal hypertension, and
  end-stage liver disease. First-line treatment is the Kasai hepatoportoenterostomy;
  most patients ultimately require liver transplantation.

parents:
  - Neonatal Cholestasis

classifications:
  harrisons_chapter:
    - classification_value: GASTROINTESTINAL

has_subtypes:
  - name: Isolated BA
    display_name: Isolated (non-syndromic) biliary atresia
    description: >-
      The most common form (roughly 70-85% of cases), presenting as isolated
      obliterative cholangiopathy without associated congenital anomalies. Often
      referred to as the perinatal form when jaundice appears after an initial
      anicteric period, implicating a postnatal/acquired inflammatory or infectious
      trigger.
  - name: BASM
    display_name: Biliary atresia splenic malformation syndrome
    description: >-
      An embryonic/fetal, syndromic form (~10-15% of cases) associated with
      laterality defects — polysplenia or asplenia, situs inversus/abdominal
      heterotaxy, a preduodenal portal vein, absent inferior vena cava, intestinal
      malrotation, and cardiac defects. Implicates disrupted left-right patterning
      and bile duct morphogenesis during embryogenesis; associated with earlier
      onset and worse outcome.
  - name: CBA
    display_name: Cystic biliary atresia
    description: >-
      A less common form in which the obliterated extrahepatic biliary tree contains
      a cyst; may be detected on prenatal or postnatal ultrasound and must be
      distinguished from a choledochal cyst, which has a much better prognosis.

inheritance:
  - name: Non-Mendelian / multifactorial
    description: >-
      Biliary atresia is overwhelmingly sporadic and non-Mendelian: twin studies
      show very high discordance (including monozygotic pairs) and familial
      recurrence is rare, implicating gene-environment, epigenetic, or stochastic
      contributions on top of genetic susceptibility. The syndromic BASM subtype
      with biallelic PKD1L1 variants is the exception, suggesting an autosomal
      recessive contribution in that specific form.
    inheritance_term:
      preferred_term: Non-Mendelian inheritance
      term:
        id: HP:0001426
        label: Non-Mendelian inheritance
    evidence:
      - reference: PMID:32504124
        reference_title: "Biliary atresia in twins: a systematic review and meta-analysis."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "97.1% twins were discordant, among 55.9% of which were monozygotic twin sets, indicating that BA may be related to genetic phenotype or penetrance."
        explanation: >-
          High monozygotic-twin discordance argues against simple Mendelian
          inheritance, supporting a non-Mendelian/multifactorial model.

prevalence:
  - population: South Korea (nationwide birth cohort)
    measure_type: BIRTH_PREVALENCE
    prevalence_class: BAND_1_5_PER_10000
    rate_per_100000: 10.6
    notes: >-
      1.06 cases per 10,000 live births in Korea. Incidence is markedly higher in
      East Asia (Taiwan/Japan) than in Europe (~5-25 per 100,000). A female
      predominance is reported (adjusted prevalence ratio 1.68, 95% CI 1.33-2.12).
    evidence:
      - reference: PMID:28244293
        reference_title: "Epidemiology of Biliary Atresia in Korea."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "The overall incidence of BA was 1.06 cases per 10,000 live births."
        explanation: >-
          National cohort birth prevalence/incidence figure for biliary atresia in
          an East-Asian population.
      - reference: PMID:35364097
        reference_title: "The Epidemiology of Biliary Atresia: Exploring the Role of Developmental Factors on Birth Prevalence."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Biliary atresia was positively associated with female sex (adjusted PR, 1.68; 95% CI, 1.33-2.12)"
        explanation: >-
          Documents the female predominance of biliary atresia birth prevalence.

pathophysiology:
  - name: Cholangiocyte Injury of the Bile Duct Epithelium
    biological_scale: CELLULAR
    description: >-
      The initiating lesion is injury to the cholangiocytes lining the extrahepatic
      (and later intrahepatic) bile ducts. Candidate insults include perinatal
      hepatotropic viral infection (cytomegalovirus, reovirus, rotavirus), exposure
      to a plant/environmental toxin (the isoflavonoid biliatresone, which causes an
      analogous extrahepatic cholangiopathy in livestock and zebrafish), and
      defective bile duct morphogenesis. Cholangiocyte apoptosis and loss of
      epithelial integrity expose ductal antigens and initiate the downstream
      inflammatory cascade.
    cell_types:
      - preferred_term: extrahepatic cholangiocyte
        term:
          id: CL:0019020
          label: extrahepatic cholangiocyte
      - preferred_term: intrahepatic cholangiocyte
        term:
          id: CL:0002538
          label: intrahepatic cholangiocyte
    biological_processes:
      - preferred_term: cholangiocyte apoptotic process
        modifier: INCREASED
        term:
          id: GO:1902488
          label: cholangiocyte apoptotic process
    evidence:
      - reference: PMID:23844248
        reference_title: "Rotavirus replication in the cholangiocyte mediates the temporal dependence of murine biliary atresia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
        explanation: >-
          The rhesus rotavirus murine model reproduces human BA by infecting neonatal
          cholangiocytes, supporting a perinatal viral cholangiocyte insult as an
          initiating mechanism.
      - reference: PMID:27102575
        reference_title: "Glutathione antioxidant pathway activity and reserve determine toxicity and specificity of the biliary toxin biliatresone in zebrafish."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
        explanation: >-
          The plant toxin biliatresone selectively injures extrahepatic cholangiocytes,
          demonstrating that a targeted cholangiocyte insult can initiate a BA-like
          extrahepatic cholangiopathy.
    downstream:
      - target: Immune-Mediated Periductal Inflammation
        description: >-
          Cholangiocyte injury exposes ductal antigens and releases danger signals
          that trigger the periductal innate and adaptive immune response.

  - name: Immune-Mediated Periductal Inflammation
    biological_scale: TISSUE
    description: >-
      Following the initial cholangiocyte insult, a Th1-polarized (interferon-gamma
      driven) and Th17-associated inflammatory response targets the bile duct
      epithelium. Portal tracts are infiltrated by CD4+ and cytotoxic CD8+ T cells,
      macrophages, and NK cells; a relative deficiency of regulatory T cells is
      thought to permit an autoimmune-like attack on the duct. This immune-mediated
      periductal inflammation amplifies and perpetuates the epithelial injury that
      began the disease.
    cell_types:
      - preferred_term: T-helper 1 cell
        term:
          id: CL:0000545
          label: T-helper 1 cell
      - preferred_term: cytotoxic T cell
        term:
          id: CL:0000910
          label: cytotoxic T cell
      - preferred_term: T-helper 17 cell
        term:
          id: CL:0000899
          label: T-helper 17 cell
      - preferred_term: macrophage
        term:
          id: CL:0000235
          label: macrophage
    biological_processes:
      - preferred_term: inflammatory response
        modifier: INCREASED
        term:
          id: GO:0006954
          label: inflammatory response
      - preferred_term: T cell mediated cytotoxicity
        modifier: INCREASED
        term:
          id: GO:0001913
          label: T cell mediated cytotoxicity
    evidence:
      - reference: PMID:39131670
        reference_title: "Regulatory T Cell (Treg) Cytotoxic T Lymphocyte-associated Antigen-4 Deficits in Biliary Atresia (BA) and Disease Rescue With Treg Augmentation in Murine BA."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Patients with BA had decreased peripheral blood Treg frequency and lack of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) upregulation despite a highly activated, effector Treg phenotype."
        explanation: >-
          Human BA patients show a regulatory T-cell deficit, supporting failed
          immune suppression permitting the autoimmune-like attack on the bile ducts.
      - reference: PMID:34943969
        reference_title: "T-Bet Deficiency Attenuates Bile Duct Injury in Experimental Biliary Atresia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Infection of newborn T-bet knockout (KO) pups with RRV resulted in a decreased Th1 inflammatory chemokine/cytokine profile when compared to infected wild-type mice."
        explanation: >-
          Genetic ablation of the Th1 master regulator T-bet blunts the Th1
          inflammatory profile, evidencing a Th1-driven mechanism of bile duct injury.
      - reference: PMID:20234283
        reference_title: "Macrophages are targeted by rotavirus in experimental biliary atresia and induce neutrophil chemotaxis by Mip2/Cxcl2."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "we detected the virus in hepatic macrophages and found that infected macrophages promoted neutrophil chemotaxis by release of Mip2/Cxcl2 in response to RRV."
        explanation: >-
          Rotavirus-targeted hepatic macrophages drive neutrophil chemotaxis, evidencing
          the innate-immune amplification arm of periductal inflammation.
    downstream:
      - target: Portal Mesenchymal Cell Activation
        description: >-
          Sustained periductal inflammation activates fibrogenic mesenchymal cells
          in the portal tract.

  - name: Portal Mesenchymal Cell Activation
    biological_scale: CELLULAR
    conforms_to: "fibrotic_response#Mesenchymal Cell Activation"
    description: >-
      Sustained inflammation activates portal fibroblasts and transdifferentiates
      hepatic stellate cells into a myofibroblast-like, matrix-secreting phenotype —
      the organ-specific mesenchymal activation step of the conserved fibrotic
      response in the biliary atresia portal tract.
    cell_types:
      - preferred_term: hepatic stellate cell
        term:
          id: CL:0000632
          label: hepatic stellate cell
    biological_processes:
      - preferred_term: hepatic stellate cell activation
        modifier: INCREASED
        term:
          id: GO:0035733
          label: hepatic stellate cell activation
    downstream:
      - target: Fibro-obliteration of the Biliary Tree
        description: >-
          Activated mesenchymal cells deposit excess extracellular matrix, driving
          progressive fibro-obliteration of the ducts.

  - name: Fibro-obliteration of the Biliary Tree
    biological_scale: TISSUE
    conforms_to: "fibrotic_response#Excessive ECM Deposition"
    description: >-
      Activated portal myofibroblasts deposit excess extracellular matrix around and
      within the injured ducts, producing a fibro-obliterative process that
      progressively narrows and obliterates the extrahepatic biliary tree and damages
      the intrahepatic ducts, forming the characteristic fibrous remnant at the porta
      hepatis. This obliteration is the anatomic substrate that the Kasai
      portoenterostomy attempts to bypass.
    biological_processes:
      - preferred_term: collagen fibril organization
        modifier: INCREASED
        term:
          id: GO:0030199
          label: collagen fibril organization
    evidence:
      - reference: PMID:32518681
        reference_title: "Biliary atresia: pathology, etiology and pathogenesis."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Histopathological findings in liver biopsies include the expansion of the portal tracts, with edematous fibroplasia and bile ductular proliferation, with bile plugs in duct lumen."
        explanation: >-
          Portal-tract fibroplasia and ductular reaction on biopsy evidence the
          fibro-obliterative remodeling of this node.
    downstream:
      - target: Cholestasis and Progression to Biliary Cirrhosis
        description: >-
          Obliteration of the biliary tree blocks bile flow, producing cholestasis
          that progresses to biliary cirrhosis and portal hypertension.

  - name: Cholestasis and Progression to Biliary Cirrhosis
    conforms_to: "cholestatic_liver_injury#Biliary Fibrosis Progressing to Biliary Cirrhosis"
    biological_scale: ORGANISM
    description: >-
      Obliteration of the biliary tree blocks bile flow, causing cholestasis with
      accumulation of conjugated bilirubin and bile acids. Retained bile constituents
      are hepatotoxic and, together with ongoing portal fibrosis, drive progression
      to biliary cirrhosis, portal hypertension, and ultimately end-stage liver
      disease. Even after a technically successful Kasai procedure, intrahepatic
      disease frequently progresses, which is why most patients eventually require
      liver transplantation.
    biological_processes:
      - preferred_term: bile acid secretion
        modifier: DECREASED
        term:
          id: GO:0032782
          label: bile acid secretion
    evidence:
      - reference: PMID:32518681
        reference_title: "Biliary atresia: pathology, etiology and pathogenesis."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Biliary atresia is a progressive fibrosing obstructive cholangiopathy of the intrahepatic and extrahepatic biliary system, resulting in obstruction of bile flow and neonatal jaundice."
        explanation: >-
          Obstruction of bile flow producing neonatal jaundice is the cholestatic
          consequence modeled by this node, on the path to biliary cirrhosis.

phenotypes:
  - name: Conjugated hyperbilirubinemia
    description: >-
      Elevation of the direct (conjugated) bilirubin fraction due to obstructed bile
      flow; the biochemical hallmark of neonatal cholestasis and the finding that
      mandates urgent evaluation for biliary atresia.
    frequency: VERY_FREQUENT
    phenotype_term:
      preferred_term: Conjugated hyperbilirubinemia
      term:
        id: HP:0002908
        label: Conjugated hyperbilirubinemia

  - name: Prolonged neonatal jaundice
    description: >-
      Jaundice persisting beyond the first two weeks of life. In biliary atresia the
      jaundice is cholestatic (conjugated) rather than the benign unconjugated
      physiologic jaundice of the newborn.
    frequency: VERY_FREQUENT
    phenotype_term:
      preferred_term: Prolonged neonatal jaundice
      term:
        id: HP:0006579
        label: Prolonged neonatal jaundice
    evidence:
      - reference: PMID:34884377
        reference_title: "Biliary Atresia: Clinical Phenotypes and Aetiological Heterogeneity."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Biliary atresia (BA) is an obliterative condition of the biliary tract that presents with persistent jaundice and pale stools typically in the first few weeks of life."
        explanation: >-
          Persistent jaundice in the first weeks of life is the defining presenting
          feature of biliary atresia.

  - name: Acholic stools
    description: >-
      Pale, clay-colored stools reflecting the absence of bile pigment reaching the
      intestine; a key clinical sign prompting stool-color screening for biliary
      atresia.
    frequency: VERY_FREQUENT
    phenotype_term:
      preferred_term: Acholic stools
      term:
        id: HP:0011985
        label: Acholic stools
    evidence:
      - reference: PMID:34884377
        reference_title: "Biliary Atresia: Clinical Phenotypes and Aetiological Heterogeneity."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Biliary atresia (BA) is an obliterative condition of the biliary tract that presents with persistent jaundice and pale stools typically in the first few weeks of life."
        explanation: >-
          Pale (acholic) stools are part of the defining presenting signature of
          biliary atresia, reflecting absent bile pigment in the gut.

  - name: Dark urine
    description: >-
      Dark urine from renal excretion of conjugated bilirubin that cannot be
      excreted via the obstructed biliary route.
    frequency: FREQUENT
    phenotype_term:
      preferred_term: Dark urine
      term:
        id: HP:0040319
        label: Dark urine

  - name: Hepatomegaly
    description: >-
      Enlargement of the liver, typically firm, reflecting cholestasis and evolving
      fibrosis.
    frequency: FREQUENT
    phenotype_term:
      preferred_term: Hepatomegaly
      term:
        id: HP:0002240
        label: Hepatomegaly

  - name: Biliary cirrhosis
    description: >-
      Progressive secondary biliary cirrhosis resulting from persistent obstruction
      and cholestatic injury; may already be present at diagnosis and progresses
      despite surgery in many patients.
    frequency: FREQUENT
    phenotype_term:
      preferred_term: Biliary cirrhosis
      term:
        id: HP:0002613
        label: Biliary cirrhosis

  - name: Portal hypertension
    description: >-
      Elevated portal venous pressure secondary to hepatic fibrosis/cirrhosis,
      leading to splenomegaly, varices, and ascites.
    frequency: FREQUENT
    phenotype_term:
      preferred_term: Portal hypertension
      term:
        id: HP:0001409
        label: Portal hypertension

  - name: Splenomegaly
    description: >-
      Enlargement of the spleen, most often a consequence of portal hypertension;
      in the BASM subtype polysplenia may instead reflect a laterality defect.
    frequency: OCCASIONAL
    phenotype_term:
      preferred_term: Splenomegaly
      term:
        id: HP:0001744
        label: Splenomegaly

  - name: Failure to thrive
    description: >-
      Poor weight gain and growth from fat malabsorption (fat-soluble vitamin
      deficiency) and the metabolic demands of chronic liver disease.
    frequency: FREQUENT
    phenotype_term:
      preferred_term: Failure to thrive
      term:
        id: HP:0001508
        label: Failure to thrive

  - name: Polysplenia
    subtype: BASM
    description: >-
      Multiple small spleens, a defining feature of the biliary atresia splenic
      malformation (BASM) subtype, part of the laterality/heterotaxy phenotype.
    frequency: OCCASIONAL
    phenotype_term:
      preferred_term: Polysplenia
      term:
        id: HP:0001748
        label: Polysplenia

  - name: Situs inversus totalis
    subtype: BASM
    description: >-
      Mirror-image reversal of thoracic and abdominal organs, part of the laterality
      spectrum seen in the BASM subtype.
    frequency: OCCASIONAL
    phenotype_term:
      preferred_term: Situs inversus totalis
      term:
        id: HP:0001696
        label: Situs inversus totalis

  - name: Cholangitis
    description: >-
      Ascending bacterial cholangitis is a frequent complication after the Kasai
      portoenterostomy, in which the Roux limb provides a conduit for enteric
      bacteria to reach the residual intrahepatic ducts.
    frequency: FREQUENT
    phenotype_term:
      preferred_term: Cholangitis
      term:
        id: HP:0030151
        label: Cholangitis

biochemical:
  - name: Elevated conjugated (direct) bilirubin
    presence: Elevated
    context: >-
      Increased serum conjugated/direct bilirubin is the defining biochemical
      abnormality; a direct bilirubin above ~1.0 mg/dL (or >20% of total) in an
      infant warrants immediate evaluation for biliary atresia.

  - name: Elevated gamma-glutamyltransferase (GGT)
    presence: Elevated
    context: >-
      Serum GGT is characteristically high in biliary atresia, in contrast to the
      low-GGT cholestases (e.g. certain PFIC subtypes), helping to narrow the
      differential.

  - name: Elevated circulating hepatic transaminases
    presence: Elevated
    context: >-
      Mild to moderate elevation of ALT and AST reflecting hepatocellular injury
      accompanying the cholestasis.

  - name: Elevated serum matrix metalloproteinase-7 (MMP7)
    presence: Elevated
    context: >-
      Serum MMP7, secreted by injured extrahepatic cholangiocytes and involved in
      extracellular-matrix remodeling, is an emerging diagnostic biomarker that is
      elevated in biliary atresia and helps discriminate it from other causes of
      neonatal cholestasis.

diagnosis:
  - name: Abdominal ultrasonography (triangular cord sign)
    description: >-
      First-line imaging. The "triangular cord" sign — a triangular/tubular echogenic
      density cranial to the portal vein bifurcation representing the fibrotic biliary
      remnant — together with an absent, atretic, or non-contractile gallbladder is
      highly specific for biliary atresia.
    diagnosis_term:
      preferred_term: abdominal ultrasonography
      term:
        id: NCIT:C17230
        label: Ultrasound Imaging
    evidence:
      - reference: PMID:9396524
        reference_title: "A new diagnostic approach to biliary atresia with emphasis on the ultrasonographic triangular cord sign: comparison of ultrasonography, hepatobiliary scintigraphy, and liver needle biopsy in the evaluation of infantile cholestasis."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Although 17 of 20 ultrasonographic examinations from infants who had BA denoted TC, 43 ultrasonographic examinations from infants with either neonatal hepatitis (NH) or other causes of cholestasis denoted no TC, showing a diagnostic accuracy of 95% with 85% sensitivity and 100% specificity."
        explanation: >-
          The triangular cord sign on ultrasound is highly specific for biliary
          atresia in the workup of infantile cholestasis.

  - name: Hepatobiliary scintigraphy (HIDA)
    description: >-
      Technetium-99m HIDA/DISIDA scintigraphy is highly sensitive but poorly specific:
      absence of tracer excretion into the gut occurs in biliary atresia but also in
      other cholestases, whereas demonstrated gut excretion effectively excludes it.

  - name: Intraoperative cholangiography
    description: >-
      The definitive confirmatory test, demonstrating non-patency of the extrahepatic
      biliary tree; performed at exploratory laparotomy, typically immediately before
      proceeding to the Kasai portoenterostomy.
    diagnosis_term:
      preferred_term: intraoperative cholangiography
      term:
        id: NCIT:C61508
        label: Cholangiography

  - name: Infant stool color card screening
    description: >-
      A parent-administered population screening tool comparing neonatal stool color
      to a reference card during the first month of life. National programs (e.g.
      Taiwan) using it achieve earlier Kasai surgery and improved transplant-free
      survival.
    evidence:
      - reference: PMID:27015203
        reference_title: "Infant Stool Color Card Screening Helps Reduce the Hospitalization Rate and Mortality of Biliary Atresia: A 14-Year Nationwide Cohort Study in Taiwan."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Since 2004, Taiwan has implemented a national screening program that uses an infant stool color card (SCC) for the early detection of BA."
        explanation: >-
          Stool color card screening is a validated national program for early
          detection of biliary atresia.

genetic:
  - name: GPC1
    notes: >-
      Glypican-1 has been implicated as a susceptibility gene; rare variants and
      reduced dosage were associated with biliary atresia and with biliary
      developmental defects in zebrafish, linking Hedgehog signaling and bile duct
      development to disease risk. Biliary atresia is generally non-Mendelian, and
      identified genes act as susceptibility/modifier loci rather than single-gene
      causes.
    relationship_type: SUSCEPTIBILITY
    gene_term:
      preferred_term: GPC1
      term:
        id: hgnc:4449
        label: GPC1
    evidence:
      - reference: PMID:32315284
        reference_title: "Association of common variation in ADD3 and GPC1 with biliary atresia susceptibility."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Two GPC1 SNPs in high linkage disequilibrium (LD) showed nominal association with BA susceptibility (PAllele = 0.03 for rs6707262 and PAllele = 0.04 for rs6750380), and were eQTL of GPC1."
        explanation: >-
          The study's own finding is a nominal GPC1 association (and eQTL effect),
          supporting GPC1 as a susceptibility locus of modest effect.

  - name: ADD3
    notes: >-
      Variants at the ADD3 locus (adducin 3) were identified as a susceptibility
      signal in genome-wide association studies of biliary atresia, first in Asian
      populations. The high twin discordance rate underlines that BA susceptibility
      loci are modifiers of risk rather than Mendelian causes.
    relationship_type: SUSCEPTIBILITY
    gene_term:
      preferred_term: ADD3
      term:
        id: hgnc:245
        label: ADD3
    evidence:
      - reference: PMID:32315284
        reference_title: "Association of common variation in ADD3 and GPC1 with biliary atresia susceptibility."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Three SNPs in ADD3 were significantly associated with BA, and rs17095355 was the top SNP"
        explanation: >-
          ADD3 is the most strongly and reproducibly associated susceptibility locus,
          with rs17095355 the lead SNP across populations.
      - reference: PMID:32504124
        reference_title: "Biliary atresia in twins: a systematic review and meta-analysis."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "97.1% twins were discordant, among 55.9% of which were monozygotic twin sets, indicating that BA may be related to genetic phenotype or penetrance."
        explanation: >-
          Near-universal twin discordance, mostly in monozygotic pairs, evidences the
          non-Mendelian, susceptibility-plus-trigger architecture of biliary atresia.

  - name: PKD1L1
    notes: >-
      Biallelic rare variants in PKD1L1, a ciliary calcium-signaling gene required for
      left-right axis determination, were identified in children with the biliary
      atresia splenic malformation (BASM) syndrome, and zebrafish pkd1l1 loss produces
      biliary defects — implicating disrupted laterality/ciliary signaling in the
      syndromic subtype.
    relationship_type: SUSCEPTIBILITY
    subtype: BASM
    gene_term:
      preferred_term: PKD1L1
      term:
        id: hgnc:18053
        label: PKD1L1
    evidence:
      - reference: PMID:30664273
        reference_title: "Identification of Polycystic Kidney Disease 1 Like 1 Gene Variants in Children With Biliary Atresia Splenic Malformation Syndrome."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "deleterious biallelic variants in polycystic kidney disease 1 like 1 (PKD1L1), a gene associated with ciliary calcium signaling and embryonic laterality determination in fish, mice, and humans."
        explanation: >-
          Whole-exome sequencing of BASM patients identified biallelic PKD1L1 variants,
          linking a ciliary laterality gene to the syndromic subtype.
      - reference: PMID:37675454
        reference_title: "Loss of zebrafish pkd1l1 causes biliary defects that have implications for biliary atresia splenic malformation."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "These data highlight the essential role of pkd1l1 in normal development and function of the zebrafish biliary system, supporting a role for this gene as a cause of BASM."
        explanation: >-
          Zebrafish pkd1l1 loss-of-function produces biliary defects, functionally
          validating the human BASM candidate gene.

  - name: CFC1
    notes: >-
      Heterozygous CFC1 (a NODAL co-receptor governing left-right patterning) variants
      were reported at increased frequency in polysplenia-syndrome BASM patients,
      proposed as a genetic predisposition to the syndromic laterality subtype.
    relationship_type: SUSCEPTIBILITY
    subtype: BASM
    gene_term:
      preferred_term: CFC1
      term:
        id: hgnc:18292
        label: CFC1
    evidence:
      - reference: PMID:18162845
        reference_title: "CFC1 gene involvement in biliary atresia with polysplenia syndrome."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "These results suggest that heterozygous CFC1 mutation may represent a genetic predisposition to biliary atresia splenic malformation syndrome."
        explanation: >-
          Heterozygous CFC1 variants are proposed as a predisposing factor for the
          BASM laterality subtype.

environmental:
  - name: Perinatal hepatotropic viral infection
    exposure_term:
      preferred_term: viral infection
      term:
        id: ECTO:3000001
        label: exposure to virus
    description: >-
      Perinatal infection with a hepatotropic virus (cytomegalovirus, reovirus, or
      rotavirus) is a leading candidate trigger for the cholangiocyte injury and
      subsequent immune response, consistent with the seasonal clustering reported
      in some cohorts and with rotavirus induction of an experimental biliary atresia
      phenotype in newborn mice.
    evidence:
      - reference: PMID:23844248
        reference_title: "Rotavirus replication in the cholangiocyte mediates the temporal dependence of murine biliary atresia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
        explanation: >-
          Rotavirus infection of neonatal mice recapitulates human BA, supporting a
          perinatal viral trigger for the isolated form.
    influences_mechanisms:
      - target: Cholangiocyte Injury of the Bile Duct Epithelium
        environmental_effect: TRIGGERS
        causal_link_type: DIRECT
        description: >-
          Perinatal hepatotropic viral infection of cholangiocytes is a candidate
          initiating insult of the disease chain.
        evidence:
          - reference: PMID:23844248
            reference_title: "Rotavirus replication in the cholangiocyte mediates the temporal dependence of murine biliary atresia."
            supports: SUPPORT
            evidence_source: MODEL_ORGANISM
            snippet: "The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
            explanation: >-
              Rotavirus infection of neonatal cholangiocytes initiates the obstructive
              cholangiopathy, acting on the cholangiocyte-injury node.

  - name: Biliatresone toxin exposure
    exposure_term:
      preferred_term: biliatresone toxin exposure
      term:
        id: ECTO:0000537
        label: exposure to toxin
    description: >-
      Biliatresone, an isoflavonoid isolated from Dysphania plants, causes an
      extrahepatic cholangiopathy resembling biliary atresia in livestock and in
      zebrafish/organoid models, providing proof of principle that an environmental
      toxin can selectively injure the extrahepatic biliary epithelium.
    evidence:
      - reference: PMID:27102575
        reference_title: "Glutathione antioxidant pathway activity and reserve determine toxicity and specificity of the biliary toxin biliatresone in zebrafish."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
        explanation: >-
          Biliatresone's selective extrahepatic-cholangiocyte toxicity establishes that
          an environmental toxin can produce a BA-like lesion.
      - reference: PMID:38578745
        reference_title: "Low-dose biliatresone treatment of pregnant mice causes subclinical biliary disease in their offspring: Evidence for a spectrum of neonatal injury."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "It likely results from a prenatal environmental exposure that spares the mother and affects the fetus."
        explanation: >-
          Low-dose prenatal biliatresone exposure in pregnant mice supports an in-utero
          environmental "hit" that affects the fetus without overt maternal illness.
    influences_mechanisms:
      - target: Cholangiocyte Injury of the Bile Duct Epithelium
        environmental_effect: TRIGGERS
        causal_link_type: DIRECT
        description: >-
          The electrophilic toxin biliatresone selectively injures extrahepatic
          cholangiocytes, acting directly on the initiating injury node.
        evidence:
          - reference: PMID:27102575
            reference_title: "Glutathione antioxidant pathway activity and reserve determine toxicity and specificity of the biliary toxin biliatresone in zebrafish."
            supports: SUPPORT
            evidence_source: MODEL_ORGANISM
            snippet: "Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
            explanation: >-
              Biliatresone's selective extrahepatic-cholangiocyte toxicity is the toxin
              route to the cholangiocyte-injury node.

  - name: Prenatal maternal infection
    description: >-
      Population-based case-control data associate maternal intestinal and
      genitourinary tract infections during pregnancy — particularly in the third
      trimester — with an increased risk of biliary atresia in offspring, consistent
      with an in-utero inflammatory contribution to pathogenesis.
    evidence:
      - reference: PMID:38170523
        reference_title: "Maternal Prenatal Infections and Biliary Atresia in Offspring."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Results of this case-control study indicate an association between prenatal intestinal infection and genitourinary tract infection in mothers and BA occurrence in their offspring."
        explanation: >-
          A large Taiwanese case-control study links prenatal maternal gut and
          genitourinary infection to offspring biliary atresia risk.
    influences_mechanisms:
      - target: Cholangiocyte Injury of the Bile Duct Epithelium
        environmental_effect: PREDISPOSES
        causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
        description: >-
          Prenatal maternal infection is an epidemiologic risk factor thought to act
          indirectly (e.g. via maternal-fetal inflammation/dysbiosis) to predispose
          the fetal biliary epithelium to injury.
        evidence:
          - reference: PMID:38170523
            reference_title: "Maternal Prenatal Infections and Biliary Atresia in Offspring."
            supports: SUPPORT
            evidence_source: HUMAN_CLINICAL
            snippet: "Results of this case-control study indicate an association between prenatal intestinal infection and genitourinary tract infection in mothers and BA occurrence in their offspring."
            explanation: >-
              Population-scale case-control evidence that maternal prenatal infection
              predisposes offspring to biliary atresia.

treatments:
  - name: Kasai Hepatoportoenterostomy
    description: >-
      The first-line surgical treatment: the fibrous biliary remnant at the porta
      hepatis is excised and a Roux-en-Y jejunal limb is anastomosed to the exposed
      surface to re-establish bile drainage. Outcome is strongly age-dependent —
      results are best when performed before ~60 days of life. It is palliative in
      many patients but can defer or avoid transplantation.
    therapeutic_modality: SURGERY
    treatment_term:
      preferred_term: surgical procedure
      term:
        id: NCIT:C15329
        label: Surgical Procedure
    target_mechanisms:
      - target: Fibro-obliteration of the Biliary Tree
        treatment_effect: BYPASSES
        description: >-
          The portoenterostomy surgically bypasses the obliterated extrahepatic
          biliary tree, re-establishing bile drainage from the porta hepatis.
    evidence:
      - reference: PMID:36051179
        reference_title: "Biliary atresia and congenital disorders of the extrahepatic bile ducts."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "BA is always treated surgically, and performing the surgery before the age of 2 mo greatly increases its effectiveness and extends the time until the need for liver transplantation arises."
        explanation: >-
          Establishes the Kasai portoenterostomy as first-line surgery and its strong
          age-dependence (best before ~2 months).

  - name: Liver Transplantation
    description: >-
      Definitive treatment for patients who fail the Kasai procedure or progress to
      end-stage liver disease. Biliary atresia is the most common indication for
      pediatric liver transplantation worldwide.
    therapeutic_modality: SURGERY
    treatment_term:
      preferred_term: liver transplantation
      term:
        id: NCIT:C15271
        label: Liver Transplantation
    evidence:
      - reference: PMID:42486594
        reference_title: "Biliary Atresia: A Focus on the Patient Journey from Diagnosis to Transplant."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "It remains the leading indication for liver transplant in children without any disease-modifying medical therapies."
        explanation: >-
          Biliary atresia is the leading indication for pediatric liver
          transplantation, supporting transplant as the definitive therapy.

  - name: Ursodeoxycholic Acid
    description: >-
      A choleretic bile acid used adjunctively after the Kasai procedure to promote
      bile flow and reduce cholestatic injury.
    therapeutic_modality: SMALL_MOLECULE
    treatment_term:
      preferred_term: Pharmacotherapy
      term:
        id: NCIT:C15986
        label: Pharmacotherapy
      therapeutic_agent:
        - preferred_term: ursodeoxycholic acid
          term:
            id: CHEBI:9907
            label: ursodeoxycholic acid
    target_mechanisms:
      - target: Cholestasis and Progression to Biliary Cirrhosis
        treatment_effect: MODULATES
        description: >-
          As a choleretic bile acid, UDCA promotes bile flow and shifts the bile-acid
          pool to less hepatotoxic species, mitigating the cholestatic node.

  - name: Prophylactic Antibiotics for Cholangitis
    description: >-
      Antibiotic prophylaxis is commonly used after portoenterostomy to reduce the
      frequency of ascending bacterial cholangitis, and acute cholangitis episodes
      are treated with broad-spectrum antibiotics.
    treatment_term:
      preferred_term: antibiotic therapy
      term:
        id: NCIT:C15620
        label: Antibiotic Therapy

  - name: Fat-Soluble Vitamin and Nutritional Support
    description: >-
      Cholestasis causes fat malabsorption and deficiency of the fat-soluble
      vitamins A, D, E, and K; supplementation plus MCT-enriched high-calorie
      nutrition is a mainstay of supportive care to prevent deficiency and support
      growth.
    therapeutic_modality: BEHAVIORAL
    treatment_term:
      preferred_term: nutritional support
      term:
        id: NCIT:C15433
        label: Nutritional Support

  - name: Post-Kasai Corticosteroid Therapy
    description: >-
      High-dose corticosteroids after hepatoportoenterostomy have been trialed as an
      adjuvant to improve bile drainage, but the definitive multicenter START
      randomized trial found no statistically significant benefit in jaundice
      clearance and an association with earlier serious adverse events. Their use
      post-Kasai remains controversial and center-dependent.
    therapeutic_modality: SMALL_MOLECULE
    treatment_term:
      preferred_term: corticosteroid pharmacotherapy
      term:
        id: NCIT:C15986
        label: Pharmacotherapy
    evidence:
      - reference: PMID:24794368
        reference_title: "Use of corticosteroids after hepatoportoenterostomy for bile drainage in infants with biliary atresia: the START randomized clinical trial."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "high-dose steroid therapy following surgery did not result in statistically significant treatment differences in bile drainage at 6 months, although a small clinical benefit could not be excluded."
        explanation: >-
          The definitive randomized trial found no significant benefit of post-Kasai
          steroids, tempering this adjuvant's evidence base.

  - name: Maralixibat (IBAT Inhibitor)
    description: >-
      Maralixibat is an oral, minimally-absorbed ileal bile acid transporter (IBAT)
      inhibitor that lowers hepatic bile acid concentration; it is approved for
      cholestatic pruritus in Alagille syndrome and is under investigation
      specifically in biliary atresia after Kasai portoenterostomy.
    therapeutic_modality: SMALL_MOLECULE
    treatment_term:
      preferred_term: Pharmacotherapy
      term:
        id: NCIT:C15986
        label: Pharmacotherapy
    evidence:
      - reference: PMID:32653991
        reference_title: "Ileal bile acid transporter inhibition as an anticholestatic therapeutic target in biliary atresia and other cholestatic disorders."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "IBAT inhibitors may potentially lessen or delay liver damage associated with the hepatotoxicity and cholangiopathy of bile acid accumulation."
        explanation: >-
          Provides the mechanistic rationale for IBAT inhibition (maralixibat) as an
          anticholestatic strategy in biliary atresia.
    target_mechanisms:
      - target: Cholestasis and Progression to Biliary Cirrhosis
        treatment_effect: INHIBITS
        description: >-
          IBAT (ASBT/SLC10A2) inhibition blocks ileal bile-acid reuptake, lowering
          the hepatic bile-acid pool that drives the cholestatic-injury node.

  - name: N-Acetylcysteine (post-Kasai)
    description: >-
      Short-course intravenous N-acetylcysteine (150 mg/kg/day for 7 days starting
      post-Kasai) was evaluated in a Phase 2 minimax-design trial aiming to normalize
      total serum bile acids; the primary endpoint was not met, though NAC was
      well-tolerated. Its mechanistic rationale comes from single-cell RNA-seq showing
      NAC partially reverses hepatic CD177+ neutrophil immune dysfunction in BA.
    therapeutic_modality: SMALL_MOLECULE
    treatment_term:
      preferred_term: Pharmacotherapy
      term:
        id: NCIT:C15986
        label: Pharmacotherapy
      therapeutic_agent:
        - preferred_term: N-acetyl-L-cysteine
          term:
            id: CHEBI:28939
            label: N-acetyl-L-cysteine
    evidence:
      - reference: PMID:40489761
        reference_title: "A phase 2 trial of short-term intravenous N-acetylcysteine in biliary atresia after Kasai portoenterostomy."
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "Although the primary endpoint was not met, NAC therapy was generally well-tolerated."
        explanation: >-
          A Phase 2 trial of post-Kasai NAC did not meet its bile-acid endpoint but
          established tolerability, tempering the evidence for this adjuvant.

clinical_trials:
  - name: NCT04524390
    phase: PHASE_II
    status: ACTIVE_NOT_RECRUITING
    description: >-
      Randomized, double-blind, placebo-controlled Phase 2 study of the IBAT inhibitor
      maralixibat in infants with biliary atresia after hepatoportoenterostomy
      (Breakthrough Therapy designation for biliary atresia).
    evidence:
      - reference: clinicaltrials:NCT04524390
        reference_title: "Randomized, Double-Blind, Placebo-Controlled Phase 2 Study to Evaluate the Efficacy and Safety of Maralixibat in the Treatment of Subjects With Biliary Atresia After Hepatoportoenterostomy"
        supports: SUPPORT
        evidence_source: HUMAN_CLINICAL
        snippet: "A study to evaluate the efficacy and safety of maralixibat in infants with Biliary Atresia (BA) after Hepatoportoenterostomy (HPE, also known as the Kasai procedure)."
        explanation: >-
          Registers the Phase 2 maralixibat post-Kasai trial referenced by the
          maralixibat treatment entry.

animal_models:
  - name: Rhesus rotavirus (RRV) neonatal mouse model
    species: Mouse
    genotype: Wild-type BALB/c neonate infected with rhesus rotavirus
    description: >-
      The canonical experimental model of biliary atresia: infection of newborn mice
      with rhesus rotavirus produces an obstructive extrahepatic cholangiopathy that
      mirrors the human disease, with cholangiocyte infection, periductal
      inflammation, and progressive duct obliteration.
    publication: PMID:23844248
    modeled_mechanisms:
      - target: Cholangiocyte Injury of the Bile Duct Epithelium
        relationship: RECAPITULATES
        fidelity: MODERATE
        description: >-
          Rotavirus replication in cholangiocytes initiates the obstructive
          cholangiopathy, reproducing the cholangiocyte-injury and duct-obliteration
          sequence of human biliary atresia.
        limitations: >-
          The model is driven by a single defined virus in an inbred neonatal mouse
          and is time-window restricted; it may not capture the etiologic
          heterogeneity or the developmental (BASM) forms of human disease.
        evidence:
          - reference: PMID:23844248
            reference_title: "Rotavirus replication in the cholangiocyte mediates the temporal dependence of murine biliary atresia."
            supports: SUPPORT
            evidence_source: MODEL_ORGANISM
            snippet: "The murine model of BA, which mirrors the human disease, is based upon infection of newborn mice with rhesus rotavirus (RRV), leading to an obstructive cholangiopathy."
            explanation: >-
              Establishes the RRV neonatal-mouse model as recapitulating the human
              cholangiocyte-injury/obstruction mechanism.

  - name: Biliatresone zebrafish model
    species: Zebrafish
    genotype: Wild-type larvae exposed to the isoflavonoid toxin biliatresone
    description: >-
      Exposure of zebrafish larvae to the plant toxin biliatresone selectively
      injures the extrahepatic biliary epithelium, providing a toxin-driven model of
      the extrahepatic cholangiopathy of biliary atresia.
    publication: PMID:27102575
    modeled_mechanisms:
      - target: Cholangiocyte Injury of the Bile Duct Epithelium
        relationship: RECAPITULATES
        fidelity: MODERATE
        description: >-
          Biliatresone reproduces selective extrahepatic-cholangiocyte injury,
          modeling the toxin route to the cholangiocyte-injury node.
        limitations: >-
          Zebrafish biliary anatomy differs from the human extrahepatic tree, and the
          specific human relevance of biliatresone exposure remains unproven; the
          model captures the injury mechanism rather than human etiology.
        evidence:
          - reference: PMID:27102575
            reference_title: "Glutathione antioxidant pathway activity and reserve determine toxicity and specificity of the biliary toxin biliatresone in zebrafish."
            supports: SUPPORT
            evidence_source: MODEL_ORGANISM
            snippet: "Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae."
            explanation: >-
              Demonstrates selective extrahepatic-cholangiocyte toxicity, grounding
              the toxin model of the injury node.

datasets:
📚

References & Deep Research

Deep Research

1
Claude Code ▸
Biliary Atresia: Comprehensive Disease Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 84 citations 2026-08-12T23:49:06.656154

Biliary Atresia: Comprehensive Disease Research Report

1. Disease Information

Overview. Biliary atresia (BA) is a rare, idiopathic, progressive fibro-obliterative cholangiopathy of infancy that destroys the extrahepatic bile ducts (and, in later stages, the intrahepatic ducts), producing complete obstruction of bile flow. It is the most common cause of neonatal cholestasis requiring surgery and the leading indication for pediatric liver transplantation worldwide. Untreated, it progresses to biliary cirrhosis and hepatic failure within the first 1–2 years of life (StatPearls; PMC7273417).

Key identifiers: - OMIM: 210500 — "BILIARY ATRESIA, EXTRAHEPATIC; EHBA" (OMIM Clinical Synopsis) - Orphanet: ORPHA:498345 (Biliary atresia and associated disorders, umbrella), ORPHA:30391 (Isolated biliary atresia), ORPHA:498350 (Syndromic biliary atresia) (Orphanet) - ICD-11: LB20.21 (biliary atresia) - MONDO: MONDO:0008867 - MeSH: D001656 (Biliary Atresia)

Synonyms: Extrahepatic biliary atresia (EHBA); congenital biliary atresia; progressive obliterative cholangiopathy of infancy; biliary atresia splenic malformation (BASM) syndrome for the syndromic laterality-defect subtype.

Evidence base: Information is derived from a mixture of aggregated disease-level resources — national/regional registries (Taiwan, Korea, France, UK, Saudi Arabia, US Western Pediatric Surgery Research Consortium), multicenter cohort studies (e.g., ChiLDReN network in the US), case-control epidemiologic studies (National Birth Defects Prevention Study), and mechanistic studies in animal/organoid models — rather than single-patient EHR extraction. Genetic findings come from case series, exome-sequencing trio studies, and GWAS meta-analyses.

Sources: Orphanet, OMIM, GARD, StatPearls

2. Etiology

BA is now understood as a final common phenotype reached via multiple distinct pathogenic routes rather than a single-cause disease (PMC8658215 — "Biliary Atresia: Clinical Phenotypes and Aetiological Heterogeneity"):

Disease Causal Factors (mechanistic/etiologic subtypes)

  1. Isolated (non-syndromic) BA (~80–90% of cases) — thought to arise from a perinatal insult (viral infection, toxin) superimposed on a susceptible genetic background, triggering an aberrant innate/adaptive immune attack on cholangiocytes.
  2. Syndromic BA / Biliary Atresia Splenic Malformation (BASM) syndrome (~10–20%) — a laterality/ciliopathy disorder with situs anomalies (polysplenia/asplenia, malrotation, interrupted inferior vena cava, cardiac defects, preduodenal portal vein), attributed to disrupted left-right patterning during early embryogenesis (embryonic/fetal-form BA, often diagnosed prenatally or at birth without a jaundice-free interval) (PMC6579603).
  3. Cystic biliary atresia — a cyst is present within an otherwise atretic biliary remnant, sometimes detectable prenatally.
  4. Cytomegalovirus (CMV)-associated BA — a subgroup with elevated anti-CMV IgM, later disease onset, higher GGT, and possibly worse Kasai outcomes.
  5. Toxin-associated (biliatresone) BA — the paradigm from naturally occurring livestock disease.

Genetic Risk Factors

  • GWAS-implicated common variants: ADD3 (adducin 3) — top SNP rs17095355, replicated across Chinese, Thai, and Caucasian cohorts as an eQTL; GPC1 (glypican 1) — rs6707262/rs6750380; ARF6; and EFEMP1 (2p16.1 locus, a GWAS hit in a European cohort) (PMC7202506; PMC6107291). Zebrafish knockdown of these genes impairs bile excretion and intrahepatic biliary network formation, functionally validating the GWAS signal.
  • BASM/laterality genes: CFC1 (Cryptic Family 1, NODAL co-receptor) — heterozygous mutations reported in familial heterotaxy/BASM (PMID:18162845; PMID:31633655); PKD1L1 — biallelic rare variants in 5 BASM subjects, a ciliary calcium-signaling gene involved in left-right axis determination, with zebrafish pkd1l1 loss producing biliary defects (PMC6642859; PMC10581383).
  • De novo / rare candidate variants from exome sequencing: STIP1 and REV1 (HSP90 co-chaperone / DNA-repair pathway, modulate biliatresone toxicity in zebrafish and human cholangiocytes) in one 30-trio cohort, not replicated in a separate 54-trio Asian cohort; additional candidate genes AMER1, INVS, OCRL, PCNT, KIF3B, TTC17 from family-based sequencing, reflecting genetic heterogeneity (Nature Sci Rep 2021; PMC7026070).
  • Copy number variation: a candidate susceptibility region at 2q37.3 (PMC2914625).
  • Overall inheritance is non-Mendelian/multifactorial: 97.1% of twin pairs are discordant (55.9% of discordant pairs monozygotic), and familial recurrence is rare (>30 multiplex families reported worldwide), implying gene–environment or epigenetic/stochastic contributions on top of genetic susceptibility (PMID:32504124; PMID:2993572).

Environmental Risk Factors

  • Prenatal maternal infection: intestinal and genitourinary tract infections during pregnancy significantly associated with offspring BA in a case-control study (447 cases / 2,912 controls) (PMC10765264).
  • Maternal metabolic/behavioral factors: maternal type 2 diabetes (OR 2.17, 95% CI 1.04–4.53) and non-dependent drug abuse (OR 3.02, 95% CI 1.34–6.78) associated with increased BA risk; maternal smoking, advanced maternal age, mode of delivery, and singleton vs. multiple pregnancy were not significantly associated (Pediatr Res 2022).
  • Plant/environmental toxin exposure (biliatresone): an isoflavonoid electrophile from Dysphania spp. plants ("pigweed") causally linked to BA-like outbreaks in lambs and calves grazing during Australian droughts; low-dose prenatal biliatresone exposure in pregnant mice causes subclinical biliary injury in offspring, supporting an in-utero "hit" model even without overt maternal illness (PMC10997102; Penn Today; Biliatresone Wikipedia).
  • Viral infection: rotavirus (particularly group C and rhesus rotavirus, RRV) and reovirus have long been implicated as perinatal triggers of the isolated form, based on the RRV murine model recapitulating human disease (see Mechanism section).

Protective Factors

No well-established genetic or environmental protective factors have been identified in the literature reviewed; this remains an evidence gap. gnomAD-level population allele-frequency data for candidate risk loci have not been systematically surveyed for protective alleles.

Gene-Environment Interactions

The leading hypothesis is a "two-hit" or susceptibility-plus-trigger model: a genetically susceptible fetus/neonate (e.g., variants affecting glutathione/redox handling, ciliary/laterality genes, or bile duct development) is exposed to an environmental insult (viral infection or toxin) during a critical developmental window, precipitating cholangiocyte injury that is then amplified by an aberrant innate/adaptive immune response (PMC9277099 — "Genetic Factors and Their Role in the Pathogenesis of Biliary Atresia"; PMC5251204 — glutathione pathway determines biliatresone susceptibility).

Suggested ontology terms: GENO:0000840 (susceptibility), MONDO:0008867, causal genes hgnc:238 (ADD3), hgnc:4451 (GPC1), hgnc:9820 (PKD1L1), hgnc:1904 (CFC1), hgnc:11376 (STIP1), hgnc:9958 (REV1); exposure term ECTO biliatresone/plant-toxin ingestion (no confirmed ECTO ID identified in this search — verify locally with OAK).

3. Phenotypes

Core presenting triad (symptoms/signs)

Phenotype Onset Frequency Suggested HPO
Persistent/progressive jaundice beyond 2 weeks of age Neonatal (2–8 weeks) Nearly universal HP:0000952 Jaundice
Acholic (pale/clay-colored) stools Presents ~2 weeks, unequivocal by 1 month Very frequent HP:0011016 (abnormal stool color) / consider a more specific acholic-stool term if available in HPO
Dark urine Concurrent with jaundice Very frequent HP:0031829 or general "abnormal urine color" term
Conjugated (direct) hyperbilirubinemia Neonatal Universal (defining lab finding) HP:0002904 Hyperbilirubinemia (specify conjugated)
Hepatomegaly Progressive over weeks Frequent HP:0002240 Hepatomegaly
Elevated serum GGT Neonatal Frequent, diagnostic clue HP:0004431 Elevated hepatic transaminase / GGT-specific lab term
Splenomegaly (as fibrosis/portal hypertension develops) Later infancy Occasional-to-frequent as disease progresses HP:0001744 Splenomegaly

Source: AASLD; PMC8658215; PMC9297290

BASM/syndromic-form associated anomalies (laterality defects)

  • Polysplenia or asplenia — HP:0009806 / HP:0001746
  • Situs inversus / midline liver — HP:0003363
  • Interrupted inferior vena cava, preduodenal portal vein
  • Cardiac malformations: dextrocardia, Tetralogy of Fallot — HP:0001671
  • Intestinal malrotation — HP:0002566

Later/progressive phenotypes (laboratory + clinical)

  • Cirrhosis and portal hypertension — HP:0001394
  • Ascites — HP:0001541
  • Coagulopathy (fat-soluble vitamin K malabsorption) — HP:0001928
  • Failure to thrive/growth failure — HP:0001508
  • Pruritus (from cholestasis)
  • Variceal bleeding in advanced disease
  • Cholangitis (recurrent, post-Kasai) — a major post-surgical complication

Phenotype characteristics

  • Age of onset: Neonatal, typically apparent by 2–8 weeks of life; the embryonic/fetal (BASM) form may be evident at birth without a preceding period of normal-colored stool, whereas the perinatal/isolated form classically has a jaundice-free interval before onset.
  • Severity/progression: Uniformly progressive if untreated — obliterative fibrosis of the biliary tree advances to biliary cirrhosis; rate varies, but historically <10% survival to age 3 without surgical intervention.
  • Frequency among affected individuals: The core triad (jaundice, acholic stool, dark urine, conjugated hyperbilirubinemia) is present in essentially 100% of cases by definition; BASM-associated anomalies occur in an estimated 10–20% of the total BA population.
  • Quality of life impact: Even with successful Kasai surgery, many children experience chronic pruritus, growth impairment, recurrent cholangitis, and portal hypertension; those progressing to transplant face lifelong immunosuppression-related morbidity. Specific standardized QOL instrument data (EQ-5D/SF-36) for BA were not surfaced in this search and represent a gap.

Sources: AASLD Pathology Pearls, PMC9297290, PMC8658215

4. Genetic/Molecular Information

Note: Unlike a classic monogenic Mendelian disease, BA has no single OMIM-cataloged causal gene; genetic contributions are best characterized as susceptibility loci (isolated form) and candidate causal genes for the BASM subtype (see §2). No pathogenic variant is required for diagnosis; genetic testing is used mainly to detect syndromic/laterality-associated variants or to exclude genetic cholestasis mimics (e.g., Alagille syndrome, PFIC).

  • GWAS susceptibility genes (isolated BA): ADD3 (hgnc:238), GPC1 (hgnc:4451), ARF6, EFEMP1 — common variants, modest effect sizes, functionally validated in zebrafish knockdown models showing impaired bile excretion/intrahepatic biliary network formation (PMC7202506; PMC6107291).
  • BASM candidate genes: PKD1L1 (biallelic, likely recessive-acting rare variants; hgnc:9820), CFC1 (heterozygous, laterality; hgnc:1904).
  • De novo/rare candidate genes (heterogeneous, not fully replicated): STIP1, REV1 (HSP90 co-chaperone pathway), AMER1, INVS, OCRL, PCNT, KIF3B, TTC17.
  • Structural variation: candidate CNV region at 2q37.3.
  • Somatic vs. germline: All reported variants are germline; no somatic mosaicism mechanism has been established, though maternal microchimerism (transfer of maternal cells/DNA to the fetus) has been proposed as a non-Mendelian contributor to phenotypic heterogeneity (PMC9539747).
  • Functional consequences: Susceptibility variants are largely regulatory/eQTL in nature (ADD3, GPC1) rather than classic loss-of-function coding lesions; PKD1L1/CFC1 variants act through disrupted ciliary/laterality signaling.
  • Allele frequency in population databases: Specific gnomAD allele frequencies for the implicated SNPs were not retrieved in this search — recommend direct gnomAD/dbSNP lookup for rs17095355 (ADD3) and rs6707262/rs6750380 (GPC1) before curation.
  • Epigenetics: Twin discordance (97% discordant, over half monozygotic) strongly implicates epigenetic and/or environmental-timing factors rather than pure genetic determinism; no specific DNA methylation signature for BA was identified in this search (gap — worth checking DiseaseMeth/Roadmap Epigenomics directly).
  • Chromosomal abnormalities: No recurrent aneuploidy or translocation syndrome is a major cause of isolated BA; BA has been reported in association with trisomy 18 and other syndromic states in isolated case reports, but this is not a primary etiologic pathway.

Suggested ontology terms: GO:0007368 (determination of left/right symmetry) for laterality-gene mechanism; HGNC gene IDs above; MONDO:0008867 disease term; consider GENO:0000845 (susceptibility to) relationship type for ADD3/GPC1/EFEMP1/ARF6 rather than a strict causal relationship.

Sources: PMC9277099, PMC6579603, Nature Sci Rep 2021

5. Environmental Information

  • Environmental toxin: Biliatresone (isoflavonoid electrophile, Dysphania spp. plants) — causally established in a naturally-occurring livestock (sheep/cattle) BA-like disease during Australian droughts; reactive α-methylene ketone group depletes cellular glutathione (GSH) selectively in extrahepatic cholangiocytes (Biliatresone – Wikipedia; PMC5251204). No confirmed direct human dietary exposure pathway has been established, but the model strongly supports plausibility of an as-yet-unidentified human environmental toxin.
  • Infectious agents (perinatal triggers): Rotavirus (particularly rhesus rotavirus, RRV, and human group C rotavirus), reovirus, cytomegalovirus (CMV) — implicated as initiators of the perinatal/isolated form via cholangiocyte infection and secondary autoimmune-like injury (see Mechanism, §6). CMV-associated BA is recognized as a distinct clinical subgroup with different serology and possibly worse prognosis.
  • Maternal infections: intestinal and genitourinary infections during pregnancy — increased offspring BA risk in case-control data (PMC10765264).
  • Maternal lifestyle/health factors: type 2 diabetes mellitus and non-dependent drug abuse increased risk; smoking, advanced maternal age, delivery mode, and singleton/multiple pregnancy showed no significant association (Pediatr Res 2022).
  • Geography/seasonality: BA incidence shows marked geographic variation (see §9), and some studies have examined birth-season clustering consistent with a seasonal infectious trigger, though this was not directly confirmed in the sources retrieved here.

Sources: PMC10997102, Penn Today, PMC10765264

6. Mechanism / Pathophysiology

BA pathogenesis is best modeled as a causal chain: developmental susceptibility → perinatal insult (viral/toxin) → cholangiocyte injury → innate immune activation → adaptive (Th1/Th17) autoimmune-like amplification → progressive fibro-obliteration → cirrhosis/liver failure.

Upstream: Developmental susceptibility (BASM subtype)

  • Disrupted left-right patterning/ciliary signaling during early embryogenesis (CFC1/NODAL pathway, PKD1L1 ciliary calcium signaling) causes combined biliary and laterality (splenic, cardiac, situs) malformation. Cholangiocyte primary cilia in BA livers are shortened, disoriented, and reduced in number, implicating ciliary dysfunction directly in bile duct pathogenesis (ResearchGate PKD1L1).
  • Suggested GO term: GO:0007368 determination of left/right symmetry.

Trigger: Cholangiocyte injury

  • Viral route (murine RRV model, isolated BA paradigm): Rhesus rotavirus infects and replicates within neonatal mouse cholangiocytes, producing an obstructive cholangiopathy that closely mirrors human BA; the temporal window of susceptibility to RRV parallels human disease timing (PMC3700947). Rotavirus infection of human cholangiocytes in vitro reproduces key features of the murine model.
  • Toxin route (biliatresone model): The electrophilic toxin binds/depletes reduced glutathione (GSH) selectively in extrahepatic cholangiocytes, inducing redox stress, disrupted protein quality control (heat-shock chaperone HSP90 pathway — STIP1, involving REV1), microtubule instability, and altered Wnt and Hippo signaling pathways, converging on cholangiocyte cytoskeletal collapse, loss of cell polarity, and lumen obstruction (Pediatric Research 2024; PMC7200694).
  • Suggested GO terms: GO:0006749 (glutathione metabolic process), GO:0016055 (Wnt signaling pathway), GO:0035329 (Hippo signaling), GO:0007017 (microtubule-based process).

Amplification: Innate and adaptive immune injury

  • Injured cholangiocytes secrete IL-1β, IL-6, IL-23, and multiple chemokines, driving Th17 commitment (IL-1β/IL-6) and sustained Th17 responses (IL-23) (Frontiers Immunology — Innate Immunity and Pathogenesis of BA).
  • Macrophages are directly targeted by rotavirus and induce neutrophil chemotaxis via Mip2/Cxcl2 (PMID:20234283).
  • The liver develops a T-helper 1 (Th1)-dominant inflammatory profile, mirrored between human BA liver and RRV-infected mouse liver; T-bet deficiency attenuates bile duct injury, and T-bet⁺/Th1-driven bile duct injury is restrained by regulatory T cells, indicating a Treg/Th1 balance central to disease severity (PMC8700492).
  • A dendritic cell–Th17–macrophage axis controls cholangiocyte injury and disease progression in both mouse and human BA.
  • B cells contribute: B-cell-deficient mice are protected from biliary obstruction in the RRV model, implicating a humoral/antibody-mediated component (PMC3749125).
  • Recent single-cell/spatial transcriptomic work (2022–2025) has resolved the fibrotic immune niche: intermediate CD14++CD16+ monocytes, scar-associated macrophages, NK T cells, transitional B cells, FCN3+ neutrophils, and CD177+ neutrophil activation are enriched in BA liver, with N-acetylcysteine (NAC) treatment partially reversing this immune dysfunction (JHEP Reports 2023; PMC9636046).
  • Suggested GO/CL terms: GO:0042093 (T-helper cell differentiation), CL:0000899 (Th17 cell), CL:0000545 (Th1 cell), CL:0000097 (mast cell)/CL:0000235 (macrophage), CL:0000097.

Downstream: Structural/cellular consequences

  • Hepatocyte-to-cholangiocyte reprogramming: single-cell RNA-seq identifies reprogrammed liver cells co-expressing hepatocyte and cholangiocyte markers; upregulated MMP7, VTCN1, LAMC2 as biliary markers and KLF5, HNF1B as biliary transcription factors in BA (PMC12055120). MMP7 in particular is an emerging serum biomarker.
  • Extrahepatic cholangiocyte damage leads to progressive peribiliary fibrosis, ductular reaction, and eventual biliary cirrhosis, portal hypertension, and hepatic failure — a convergence with the dismech fibrotic_response module logic (tissue injury → inflammation → mesenchymal/myofibroblast activation → excessive ECM → organ dysfunction).
  • Organoid studies show BA-derived extrahepatic cholangiocyte organoids exhibit increased ER and oxidative stress, altered drug metabolism, and cell-polarity changes relative to controls (bioRxiv 2025).

Anatomical developmental context

The extrahepatic bile ducts (common bile duct, cystic duct, gallbladder) derive from the pars cystica of the liver bud, developmentally and transcriptomically distinct from the intrahepatic ducts (pars hepatica); this distinct origin is consistent with BA being fundamentally an extrahepatic-duct disease that can secondarily involve intrahepatic ducts as fibrosis ascends (PMC8604670).

Suggested overall causal-chain GO/CL/UBERON scaffold for a dismech pathophysiology block: 1. Node: "Perinatal Cholangiocyte Insult" (biological_scale: CELLULAR) — GO:0006749 glutathione metabolic process, viral infection trigger 2. Node: "Innate Immune Activation and Cytokine Release" — CL:0000235 macrophage, GO:0032612 IL-1 production 3. Node: "Th1/Th17-Driven Adaptive Autoimmune Amplification" — CL:0000899 Th17 cell, CL:0000545 Th1 cell 4. Node: "Extrahepatic Bile Duct Fibro-Obliteration" (biological_scale: TISSUE) — conforms_to fibrotic_response 5. Node: "Biliary Cirrhosis and Hepatic Failure" (biological_scale: ORGANISM)

Sources: Nature Reviews Gastro & Hepatology 2015, PMC7273417, PMC9277099, PMC7052372

7. Anatomical Structures Affected

Organ level: - Primary: Extrahepatic bile ducts (common bile duct, common hepatic duct, cystic duct), gallbladder, and liver (progressive secondary intrahepatic ductal and parenchymal involvement). - Secondary/complication-related: Spleen (in BASM — poly-/asplenia), heart (in BASM — situs/structural defects), portal venous system (varices, preduodenal portal vein in BASM), intestine (malrotation in BASM; post-Kasai Roux limb). - Body systems: Primarily hepatobiliary/digestive; secondarily cardiovascular (BASM) and, via chronic cholestasis, the skeletal system (rickets from fat-soluble vitamin D malabsorption) and hematologic system (coagulopathy from vitamin K malabsorption). - Suggested UBERON: UBERON:0002394 (extrahepatic bile duct region — verify exact term via OAK), UBERON:0002110 (gallbladder), UBERON:0002107 (liver), UBERON:0002106 (spleen).

Tissue and cell level: - Cholangiocytes (biliary epithelial cells) — the primary cellular target; suggested CL:0000546 or more specifically extrahepatic cholangiocyte if a CL term exists. - Peribiliary gland cells — proposed stem/progenitor niche relevant to biliary regeneration/repair. - Portal fibroblasts / hepatic stellate cells → myofibroblasts — drive the fibrotic response (conforms to fibrotic_response module: CL:0000632 hepatic stellate cell). - Hepatocytes — undergo secondary reprogramming toward a biliary phenotype in advanced disease. - Immune infiltrate: macrophages (CL:0000235), Th1/Th17 CD4+ T cells (CL:0000545/CL:0000899), B cells, NK T cells, neutrophils (including a CD177+ activated subset).

Subcellular level: - Mitochondrial/ER oxidative stress in cholangiocytes (GO:0005739 mitochondrion, GO:0005783 endoplasmic reticulum). - Cytoskeletal/microtubule disruption (GO:0005874 microtubule). - Primary cilium abnormalities in cholangiocytes (short, disoriented, reduced in number) — GO:0005929 cilium.

Localization: Disease is centered on the porta hepatis and extrahepatic biliary tree; not classically lateralized, though BASM introduces organ-level laterality anomalies (situs abnormalities) as a distinct phenotypic axis.

Sources: PMC8604670, PMC7273417

8. Temporal Development

  • Onset: Neonatal, typically manifesting clinically between 2 and 8 weeks of age (perinatal/isolated form, often with an initial jaundice-free interval as physiologic neonatal jaundice resolves and pathologic jaundice supervenes) vs. present at or near birth without a jaundice-free interval (embryonic/fetal/BASM form).
  • Onset pattern: Subacute-to-insidious in the isolated form; can be apparent congenitally in the BASM/fetal form.
  • Progression / disease stages: Uniformly progressive fibro-obliterative process — early ductular proliferation and bile plugging → periportal fibrosis → bridging fibrosis → biliary cirrhosis → portal hypertension and hepatic decompensation. Histopathologic staging at the time of Kasai portoenterostomy (degree of fibrosis, Ki67 proliferation index) is prognostically important (PMC7528526; PMC11870969).
  • Progression rate: Rapid and relentless if untreated — median survival ~8 months, near-100% mortality by 2 years, historical <10% survival to age 3 without intervention (StatPearls). With Kasai surgery, progression can be substantially slowed or, in a subset, arrested for decades.
  • Disease course pattern: Progressive; a subset of Kasai-treated patients stabilizes with the native liver, while others continue to progress to transplant despite surgery — course is not relapsing-remitting.
  • Critical period: Timing of Kasai portoenterostomy is the single most important modifiable variable — earlier surgery (ideally <45–60 days of life, before irreversible cirrhosis sets in) yields substantially better transplant-free survival (PMID:34854975).
  • Remission: No spontaneous remission is described; "remission" in the treated sense means durable native-liver survival with normalized bilirubin after Kasai (jaundice clearance, typically assessed at 3 and 6 months post-op).

Sources: Western Pediatric Surgery Research Consortium study, PMC7333324, StatPearls

9. Inheritance and Population

Epidemiology

  • Geographic variation is marked: Incidence in Taiwan/Japan is roughly 100–500 per 100,000 live births (i.e., ~0.12–0.19 per 1,000 in a 1997–2010 Taiwan cohort), versus 5–25 per 100,000 in Europe, and ~0.52–0.71 per 10,000 live births in Western literature broadly (ScienceDirect — East vs West). South Korea reports an incidence of 1.06 per 10,000 live births (J Korean Med Sci 2017).
  • Orphanet lists overall point prevalence as 1–9 per 100,000.

Inheritance pattern

  • Multifactorial / non-Mendelian, not simple autosomal dominant/recessive — reflected by high twin discordance (97.1% discordant pairs, 55.9% of these monozygotic) (PMID:32504124; PMID:2993572). Suggested HPO inheritance term: HP:0001426 (multifactorial inheritance) rather than a single Mendelian mode; syndromic BASM cases with biallelic PKD1L1 variants suggest an autosomal recessive contribution to that specific subtype.
  • Penetrance/expressivity: Because BA is not classically monogenic, formal penetrance estimates for individual variants (e.g., ADD3, GPC1) are not established; these are population susceptibility alleles with small effect sizes, not highly penetrant Mendelian variants.
  • Familial recurrence: Rare; >30 multiplex families reported worldwide, suggesting low but non-zero recurrence risk, likely elevated specifically for the genetically-driven syndromic (BASM) subtype.
  • Founder effects/consanguinity: Not prominently reported in the literature surveyed here (gap).
  • Maternal microchimerism: Proposed as a contributor to sporadic, non-Mendelian phenotypic variability (transfer of maternal cells to the fetus) (PMC9539747).

Population demographics

  • Sex ratio: Female predominance — adjusted prevalence ratio 1.68 (95% CI 1.33–2.12) for females vs. males (JPeds 2022).
  • Ethnic/geographic distribution: Substantially higher incidence in East Asian populations (Taiwan, Japan, Korea, China) than in European or North American populations; French Polynesia and some other populations also show elevated rates. The reasons for this disparity are not fully explained but are hypothesized to involve both genetic background (ADD3/GPC1 allele frequencies differ by ancestry) and environmental exposure differences.
  • Age distribution: By definition, an infantile-onset disease; no adult-onset form exists (survivors reaching adulthood on native liver represent successfully treated childhood-onset cases, not new adult presentations).

Sources: PubMed 35364097, PMC9339784 — Saudi national study, J Korean Med Sci

10. Diagnostics

Clinical/laboratory tests

  • Liver function tests: conjugated (direct) hyperbilirubinemia with markedly elevated serum gamma-glutamyl transferase (GGT) — a key discriminating lab clue from other neonatal cholestatic conditions (Geeky Medics).
  • Fractionated bilirubin is under investigation as a US newborn-screening strategy (measuring direct/conjugated bilirubin fraction abnormal in BA newborns).
  • Additional biomarkers under study: urine sulfated bile acids (USBA), serum bile acids, serum free carnitine, and serum MMP7 (matrix metalloproteinase 7, emerging from single-cell transcriptomic work as a biliary-injury marker).

Imaging

  • Abdominal ultrasound — "triangular cord" sign: a triangular/tubular echogenic density cranial to the portal vein bifurcation, representing the fibrotic biliary remnant; 85% sensitivity, 100% specificity in the original comparative study, alongside gallbladder abnormalities (absent, atretic, or non-contractile gallbladder) as the other key sonographic feature (PMID:9396524; AJR meta-analysis).
  • Hepatobiliary scintigraphy (Tc-99m-DISIDA / HIDA scan): absence of tracer excretion into the gut is 96% sensitive but only 35% specific (many non-BA cholestatic conditions also fail to excrete); presence of gut excretion effectively excludes BA.
  • Liver needle biopsy: shows bile duct proliferation, bile plugs, and portal fibrosis; 90% sensitivity, 96% specificity in comparative series — used when ultrasound/scintigraphy are equivocal.
  • Diagnostic algorithm: if the triangular cord sign is present, proceed directly to exploratory laparotomy/intraoperative cholangiogram without further workup; if absent, proceed to scintigraphy, reserving liver biopsy for infants with no tracer excretion (PMID:9396524).
  • Intraoperative cholangiogram remains the definitive confirmatory test, demonstrating non-patency of the extrahepatic biliary tree.

Genetic testing

  • Not part of routine BA diagnosis (BA is a structural/inflammatory diagnosis, not primarily a molecular one), but targeted or exome sequencing is used to evaluate syndromic (BASM) cases for laterality-gene variants (PKD1L1, CFC1) and to exclude genetic mimics of neonatal cholestasis such as Alagille syndrome (JAG1/NOTCH2), progressive familial intrahepatic cholestasis (PFIC, ATP8B1/ABCB11/ABCB4), alpha-1-antitrypsin deficiency, and citrin deficiency.

Differential diagnosis

Neonatal hepatitis, Alagille syndrome, choledochal cyst, PFIC, alpha-1-antitrypsin deficiency, inspissated bile/mucous plug syndrome, total parenteral nutrition-associated cholestasis, and various inborn errors of metabolism presenting with cholestasis.

Screening (asymptomatic detection)

  • Infant Stool Color Card (ISCC) is the most widely used population-based screening method (parent-administered, comparing stool color to a reference card during the first month of life). In Taiwan's national program: sensitivity 89.7%, specificity 99.9%, PPV 28.6%; implementation was associated with earlier Kasai surgery (66% vs. 49% performed <60 days of age) and improved 3-year jaundice-free survival (57% vs. 31.5%) versus historical controls (PMC4998398).
  • A 14-year nationwide Taiwan cohort further showed stool color card screening reduced hospitalization rates and mortality (PMC4998398).

Sources: AAP Pediatrics — Newborn Screening for BA, PMC11357077, PubMed 34817690

11. Outcome/Prognosis

Survival and mortality

  • Untreated: near-100% mortality by 2 years of age; median survival ~8 months; historical <10% survival to age 3 (StatPearls).
  • After Kasai portoenterostomy: anicteric transplant-free survival rates are approximately 60% at 5 years and 50% at 20 years; roughly 40.8% of a cohort of 223 infants survived to a defined endpoint with native liver in one series; 25–35% of Kasai patients survive >10 years without transplant in broader estimates (PMC8160257; Nature Sci Rep — Kasai follow-up).
  • Jaundice clearance: >66% of patients become jaundice-free by 1 year post-Kasai in some series; only ~40–70% achieve jaundice clearance overall, and those who fail typically progress rapidly to transplant.
  • Liver transplantation outcomes: patient/graft survival rates of 95.8%/91.0% over 20 years in one high-volume single-center study; more broadly, 5-/10-year graft survival ranges 68–98% and 71–90% respectively across centers; a separate 20-year single-center cohort reported a 63.8% cumulative 20-year graft survival (Frontiers Pediatrics 2023; PMC10940458).

Morbidity

  • Complications post-Kasai: recurrent bacterial cholangitis (common and can precipitate acute decompensation), progressive portal hypertension with variceal bleeding, pruritus, growth failure, and fat-soluble vitamin deficiencies.
  • Complications post-transplant: post-transplant lymphoproliferative disease (most frequent in the first 1–2 years of immunosuppression), and steadily increasing incidence of cholangitis and rejection over time (Frontiers Pediatrics 2023).
  • BA remains the leading indication for pediatric liver transplantation in the US and worldwide.

Prognostic factors

  • Age at Kasai surgery — earlier surgery (ideally before 45–60 days of life) associated with significantly better transplant-free survival; performance at high-volume/tertiary centers also improves outcomes (PMID:34854975).
  • Degree of liver fibrosis/cirrhosis at time of Kasai (histopathologic staging) predicts subsequent cirrhosis progression and survival (PMC7333324).
  • Ki67 proliferation index at the time of Kasai has been evaluated as a prognostic biomarker (PMC7528526).
  • Postoperative intestinal obstruction after Kasai impedes biliary excretion and predisposes to subsequent transplantation (PMC7847427).
  • CMV-associated BA and BASM-syndromic BA are generally associated with worse Kasai response/outcomes than isolated, non-CMV BA (a recurring theme across the phenotype-heterogeneity literature, though effect sizes vary by cohort).

Sources: Escholarship UCSD, medRxiv Kasai prediction cohort, ScienceDirect — long-term native liver outcomes

12. Treatment

Surgical (primary/definitive)

  • Kasai hepatoportoenterostomy — the standard first-line surgical procedure; excises the fibrotic extrahepatic biliary remnant and anastomoses a Roux-en-Y jejunal limb directly to the porta hepatis to restore bile drainage from residual microscopic ductules. Suggested NCIT term: NCIT:C154430 or a specific hepatoportoenterostomy procedure term (verify exact NCIT code via OAK); more broadly NCIT:C15329 (Surgical Procedure).
  • Liver transplantation — reserved for Kasai failure (persistent jaundice), progressive cirrhosis/liver failure, or recurrent decompensating cholangitis; both living-donor and deceased-donor transplantation are used; BA is the leading pediatric indication for liver transplant. Suggested NCIT term: NCIT:C15289 (Organ Transplantation).

Pharmacotherapy / adjuvant medical therapy

  • Ursodeoxycholic acid (UDCA) — choleretic agent, widely used adjunctively post-Kasai to promote bile flow, though robust RCT evidence specific to BA outcomes was not directly retrieved in this search (commonly used based on extrapolation from other cholestatic diseases; NCIT drug/agent term applicable under Pharmacotherapy NCIT:C15986 with CHEBI ursodeoxycholic acid as therapeutic_agent).
  • Corticosteroids (post-Kasai adjuvant): The START trial (Steroids in Biliary Atresia Randomized Trial) — multicenter, double-blind RCT, 140 infants, IV methylprednisolone (4 mg/kg/day × 2 weeks) then oral prednisolone (2 mg/kg/day × 2 weeks, tapered over 9 weeks) vs. placebo, initiated within 72 hours of Kasai. Primary result: no statistically significant benefit in the overall cohort (49% vs. 59% jaundice clearance at 6 months, direction not favoring steroids significantly); a subgroup of younger infants showed a trend toward increased jaundice clearance (71.8%) that did not reach significance (JAMA 2014; NIDDK repository). Corticosteroid use post-Kasai remains controversial/center-dependent.
  • N-acetylcysteine (NAC): Phase 2 trial of short-term IV NAC (150 mg/kg/day × 7 days, starting 0–24h post-Kasai) targeting normalization of total serum bile acids; mechanistically supported by single-cell RNA-seq data showing NAC partially reverses hepatic immune dysfunction (CD177+ neutrophil activation) in BA liver (PMC12150978; JHEP Reports 2023).
  • Maralixibat (Livmarli™) — an oral, minimally-absorbed ileal bile acid transporter (IBAT) inhibitor; FDA-approved for cholestatic pruritus in Alagille syndrome (2021) and PFIC; under late-stage clinical evaluation specifically in BA (compassionate-use case series and formal trials such as NCT04524390, "Evaluation of Maralixibat in Biliary Atresia Response Post-Kasai") with Breakthrough Therapy designation for BA; reduces serum bile acids and pruritus (Drugs — Maralixibat First Approval; Frontiers Pediatrics — Real-World Use of Maralixibat in BA). Suggested therapeutic_modality: SMALL_MOLECULE; treatment_term Pharmacotherapy; therapeutic_agent maralixibat (verify NCIT/CHEBI code).
  • Fat-soluble vitamin supplementation (A, D, E, K) — supportive care for malabsorption due to cholestasis.
  • Prophylactic antibiotics — commonly used post-Kasai to reduce cholangitis risk (center-dependent protocols).

Emerging / experimental

  • Antifibrotic agents, additional bile-acid modulators, and regenerative approaches are described as an emerging pipeline as of 2025, per industry pipeline analyses (early-stage; specific compounds/trial identifiers were not detailed in the sources retrieved) (OpenPR — Biliary Atresia Pipeline Insight 2025).
  • Gene expression signature-guided identification of repurposable therapeutic agents has been explored computationally but is not yet in clinical use.

Treatment outcomes / adverse events

  • Corticosteroids: no consistent significant efficacy signal in the definitive RCT; risk of steroid-related adverse effects (infection, growth suppression) must be weighed.
  • NAC: generally well-tolerated antioxidant; efficacy data still maturing (Phase 2).
  • Maralixibat: primarily studied for pruritus/bile-acid reduction rather than as disease-modifying for the biliary obstruction itself; diarrhea is a common adverse effect of IBAT inhibitors as a class.
  • Post-transplant immunosuppression carries standard risks (infection, PTLD, rejection).

Treatment strategy

Standard algorithm: early diagnosis (ideally via stool-color screening) → prompt Kasai hepatoportoenterostomy (<45–60 days of age) → adjuvant medical management (antibiotics, choleretics, nutritional/vitamin support, investigational NAC/steroids per center protocol) → surveillance for jaundice clearance and cholangitis → liver transplantation if Kasai fails or cirrhosis/portal hypertension progresses.

Sources: Translational Pediatrics — Adjuvant treatments for BA, PMC7347763, Frontiers Pediatrics — Current and emerging adjuvant therapies

13. Prevention

  • Primary prevention: No established method to prevent the underlying disease process, since the precise causal environmental trigger(s) in humans (analogous to biliatresone in livestock, or a specific human viral strain) remain unconfirmed. No vaccine or prophylactic intervention exists.
  • Secondary prevention (early detection, the dominant prevention strategy in practice): Universal newborn screening via the infant stool color card is the principal population-based strategy, validated most extensively in Taiwan, with adoption in Japan, parts of Europe (e.g., Switzerland), Canada (Ontario Newborn Screening), and pilot programs elsewhere. Screening enables earlier Kasai surgery and improved transplant-free survival (PMC4998398; Newborn Screening Ontario).
  • Alternative/complementary screening strategies under investigation: fractionated (direct) bilirubin measurement in the newborn period, urine sulfated bile acids, serum bile acids, and serum free carnitine (PMC11357077).
  • Tertiary prevention: Prompt Kasai surgery itself functions as tertiary prevention against progression to end-stage liver disease; post-Kasai prophylactic antibiotics aim to prevent cholangitis-driven decompensation; nutritional/vitamin support prevents secondary complications of cholestasis (rickets, coagulopathy, growth failure).
  • Genetic counseling: Given the largely sporadic, multifactorial inheritance and high twin discordance, formal genetic counseling protocols for recurrence risk are not well standardized, though counseling may be offered for the syndromic BASM subtype where recessive contributions (e.g., PKD1L1) are more plausible.
  • Public health / environmental interventions: No specific environmental intervention (analogous to removing Dysphania plants from livestock pasture) has been identified or implemented for human BA prevention, reflecting the unresolved human etiologic trigger.

Sources: AAP Pediatrics, PMC4998398

14. Other Species / Natural Disease

  • Taxonomy: Naturally occurring BA-like disease has been documented in sheep (Ovis aries, NCBITaxon:9940) and cattle (Bos taurus, NCBITaxon:9913) during Australian drought conditions, causally linked to grazing on Dysphania spp. plants (the source of biliatresone) (Penn Today; ScienceDirect — Biliary atresia: the animal models). Sporadic case reports also describe BA or BA-like biliary obstruction in foals, dogs, and calves (PMC9324346 — "Biliary Atresia Animal Models: Is the Needle in a Haystack?").
  • Veterinary relevance: The lamb outbreaks were the key discovery that led to identification of biliatresone and its mechanism, making veterinary field observation directly foundational to human BA mechanistic research — an unusually direct comparative-medicine translation.
  • OMIA: A dedicated OMIA entry specific to biliary atresia (as distinct from anal/atresia ani, OMIA:000083) was not identified in this search; this appears to be a database coverage gap rather than an absence of the phenotype in animals.
  • Comparative biology: The zebrafish (Danio rerio, NCBITaxon:7955) biliatresone model demonstrates conserved susceptibility of extrahepatic cholangiocytes across vertebrate species, and the murine RRV model demonstrates conserved rotavirus-cholangiocyte tropism and Th1/Th17 immune injury pathways, supporting deep evolutionary conservation of both the toxin-susceptibility and immune-injury arms of the mechanism.
  • Transmission/zoonotic potential: Not applicable — BA is not an infectious/transmissible disease of humans in the classic zoonotic sense; the shared susceptibility across species is due to convergent developmental/toxicologic vulnerability of extrahepatic cholangiocytes, not cross-species pathogen transmission. Rotavirus itself is zoonotically and cross-species relevant as a pathogen family, but RRV-induced murine BA is a laboratory disease model, not natural cross-species BA transmission.

Sources: PMC9324346, PMID:22800971

15. Model Organisms

Zebrafish (Danio rerio)

  • Biliatresone toxic-injury model: Larval zebrafish exposed to biliatresone develop selective destruction of the extrahepatic biliary tree, closely recapitulating human/livestock BA; toxicity is determined by glutathione antioxidant pathway activity/reserve (PMC5251204), and involves Wnt, Hippo, and microtubule pathway disruption (Pediatric Research 2024). Genetic modifiers (e.g., STIP1/REV1 pathway disruption) alter biliatresone susceptibility in this model, linking the toxin model directly to human WES candidate genes.
  • GWAS-gene knockdown models: Morpholino/CRISPR knockdown of ADD3, GPC1, and related susceptibility genes impairs bile excretion and intrahepatic biliary network formation, functionally validating human GWAS hits (PMC7202506).
  • pkd1l1 loss-of-function zebrafish: recapitulates biliary defects relevant to BASM syndrome, directly linking a human BASM candidate gene to a ciliary/biliary phenotype (PMC10581383).
  • Strengths: rapid, scalable, optically transparent for live imaging of biliary tree development; excellent for genetic-modifier and chemical-toxin screening.
  • Limitations: larval zebrafish biliary anatomy and immune system differ substantially from mammalian/human systems; does not model the adaptive Th1/Th17 autoimmune-injury arm well.

Mouse (Mus musculus)

  • Rhesus rotavirus (RRV)-induced murine BA model: the dominant immune-mediated/infectious model; neonatal mice infected with RRV develop an obstructive cholangiopathy mirroring human isolated BA, including rotavirus replication within cholangiocytes with strict temporal dependence on neonatal age at infection (PMC3700947), macrophage targeting and Mip2/Cxcl2-driven neutrophil chemotaxis (PMID:20234283), B-cell dependence (B-cell-deficient mice protected) (PMC3749125), T-bet/Th1-dependent bile duct injury restrained by regulatory T cells (PMC8700492), and a dendritic cell–Th17–macrophage disease-progression axis. A recent study further defined specific rhesus-rotavirus capsid-protein binding sites dictating the endocytosis route that induces this model (PMC11687966).
  • Biliatresone-induced murine model: the synthetic toxin also causes BA in mice, including a low-dose prenatal exposure paradigm in pregnant mice producing subclinical biliary disease in offspring — modeling a spectrum of neonatal injury severity relevant to the "environmental hit during pregnancy" human hypothesis (Lab Investigation 2020; PMC10997102).
  • Strengths: recapitulates the full innate + adaptive immune injury cascade and postnatal obstructive fibrosis; the field's primary model for immunopathogenesis and immunomodulatory drug testing.
  • Limitations: RRV is not the confirmed human causal agent (human rotavirus/other viruses are the presumed but unconfirmed human trigger); model requires precise neonatal-age infection timing, limiting some translational aspects.

Human iPSC-derived organoids / primary cholangiocyte cultures

  • Human BA extrahepatic cholangiocyte organoids show increased ER/oxidative stress, altered drug metabolism, and cell-polarity changes relative to controls, and are being used to test genetic modifiers of biliatresone toxicity identified in zebrafish (e.g., HSP90/STIP1 pathway) (bioRxiv 2025; PMC10974618 — biliatresone effects on human liver organoids).
  • Applications: direct human-cell validation bridging zebrafish/mouse mechanistic findings to human biology; useful for drug screening (e.g., NAC, glutathione-repletion strategies).

Naturally occurring large-animal models (sheep, cattle)

  • Field-derived, non-induced natural disease model that originally identified biliatresone; valuable for toxin discovery but not amenable to routine laboratory-scale genetic manipulation.

Resource databases

ZFIN (zebrafish), MGI (mouse), IMSR (mouse strain repository) are the relevant model-organism databases for locating specific BA-model alleles/lines; no dedicated BA entries were directly retrieved from these databases in this search (recommend direct query for specific allele/strain nomenclature during curation).

Sources: PMC9324346, PMC3700947, Nature Lab Investigation 2020

Summary Table: Suggested Ontology Terms for KB Curation

Category Term ID (verify via OAK before use) Label
Disease MONDO:0008867 biliary atresia
Phenotype HP:0000952 Jaundice
Phenotype HP:0002240 Hepatomegaly
Phenotype HP:0001394 Cirrhosis
Phenotype HP:0001541 Ascites
Phenotype HP:0001744 Splenomegaly
Phenotype (BASM) HP:0003363 Abnormal situs
Gene hgnc:238 ADD3
Gene hgnc:4451 GPC1
Gene hgnc:9820 PKD1L1
Gene hgnc:1904 CFC1
Cell type CL:0000899 Th17 cell
Cell type CL:0000545 Th1 cell
Cell type CL:0000632 hepatic stellate cell
Cell type CL:0000235 macrophage
GO Process GO:0006749 glutathione metabolic process
GO Process GO:0016055 Wnt signaling pathway
GO Process GO:0007368 determination of left/right symmetry
Anatomy UBERON:0002107 liver
Anatomy UBERON:0002110 gallbladder
Treatment NCIT:C15289 Organ Transplantation
Treatment NCIT:C15329 Surgical Procedure (Kasai)
Treatment NCIT:C15986 Pharmacotherapy (steroids, NAC, maralixibat, UDCA)
Model organism taxon NCBITaxon:7955 Danio rerio
Model organism taxon NCBITaxon:10090 Mus musculus

(All term/label pairs above require verification against the live ontology via OAK before committing to a dismech entry, per repository policy — this report is a research input, not pre-validated curation content.)

Key Evidence Gaps Identified

  1. No confirmed specific human environmental toxin analogous to biliatresone.
  2. No systematic gnomAD/population allele-frequency data compiled here for ADD3/GPC1 risk SNPs.
  3. No specific DNA methylation/epigenetic signature study for BA identified despite strong indirect evidence (twin discordance) for an epigenetic contribution.
  4. No standardized quality-of-life instrument (EQ-5D/SF-36/PedsQL) data specific to BA surfaced in this search.
  5. Genetic testing panels/GTR-specific BA gene panel composition not directly retrieved — recommend direct GTR query during curation.
  6. No dedicated OMIA species-specific entry located for the sheep/cattle BA-like disease despite well-documented field reports.