Caring for someone with this diagnosis? Eleplan keeps diagnoses, medications, documents and every specialist in one plan.
Start free with EleplanCongenital bile acid synthesis defect type 2
ORPHA:79303Disease
Also called BASD2 · Cholestasis with delta(4)-3-oxosteroid 5-beta-reductase deficiency
What it is
Congenital bile acid synthesis defect type 2 (BAS defect type 2) is an anomaly of bile acid synthesis characterized by severe and rapidly progressive cholestatic liver disease, and malabsorption of fat and fat-soluble vitamins.
Key facts
- Age of onset
- Infancy, Neonatal
- Inheritance
- Autosomal recessive
- Classified as
- Disease
Signs and symptoms
Common30–79%
21- Abnormality of the coagulation cascade
- Abnormal serum bile acid concentration
- Cholestasis
- Conjugated hyperbilirubinemia
- Dark urine
- Elevated circulating alkaline phosphatase concentration
- Elevated circulating hepatic transaminase concentration
- Extramedullary hematopoiesis
- Failure to thrive
- Fat malabsorption
- Hepatic failure
- Hepatic steatosis
- Hepatomegaly
- Increased circulating lactate dehydrogenase concentration
- Jaundice
- Low levels of vitamin E
- Postnatal growth retardation
- Prolonged neonatal jaundice
- Prolonged partial thromboplastin time
- Prolonged prothrombin time
- Steatorrhea
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Gene
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
Powered by Eleplan
A rare diagnosis is just the start. Eleplan keeps the whole care plan in one place.
Diagnoses, medications, documents, appointments, and the whole care team — organized and always in sync, so you are not retelling the same story to every new specialist. With Ellie, your AI care assistant, on top of it. Free to start.