Autosomal recessive
Caused by changes in both copies of the AKR1D1 gene, which makes the enzyme delta-4-3-oxosteroid 5-beta-reductase. Without it, normal bile acids are not made and abnormal, liver-damaging bile acids build up.
Signs and symptoms
Babies develop jaundice from blocked bile flow (cholestasis) in the first weeks or months of life, with pale stools and an enlarged liver. Poor fat absorption can lead to slow growth and low levels of vitamins A, D, E and K, which can cause bleeding. Without treatment, liver damage can progress to cirrhosis, which can be fatal in childhood.
What a diagnosis changes
Oral chenodeoxycholic acid replaces the missing bile acids. When started early, it can improve jaundice, liver function and liver size. Fat-soluble vitamin levels and liver function are monitored. Genetic counselling is recommended, and carrier testing is available for relatives.
Genes analysed
Also known as
AKR1D1 congenital bile acid synthesis defect; BASD2; congenital bile acid synthesis defect type 2; CBAS2; cholestasis with delta(4)-3-oxosteroid 5-beta-reductase deficiency; congenital bile acid synthesis defect caused by mutation in AKR1D1
