Congenital bile acid synthesis defect type 1

Congenital bile acid synthesis defect type 1 is a disorder characterized by cholestasis, a condition that impairs the production and release of a digestive fluid called bile from liver cells. Bile is used during digestion to absorb fats and fat-soluble vitamins, such as vitamins A, D, E, and K. People with congenital bile acid synthesis defect type 1 cannot produce (synthesize) bile acids, which are a component of bile that stimulate bile flow and help it absorb fats and fat-soluble vitamins. As a result, an abnormal form of bile is produced.

The signs and symptoms of congenital bile acid synthesis defect type 1 often develop during the first weeks of life, but they can begin anytime from infancy into adulthood. Affected infants often have a failure to gain weight and grow at the expected rate (failure to thrive) and yellowing of the skin and eyes (jaundice) due to impaired bile flow and a buildup of partially formed bile. Excess fat in the feces (steatorrhea) is an additional feature of congenital bile acid synthesis defect type 1. As the condition progresses, affected individuals can develop liver abnormalities including an enlarged liver (hepatomegaly), inflammation, or chronic liver disease (cirrhosis). The spleen may also become enlarged (splenomegaly). The inability to absorb certain fat-soluble vitamins (vitamin D in particular) can result in softening and weakening of the bones (rickets) in some individuals.

If left untreated, congenital bile acid synthesis defect type 1 often leads to cirrhosis and death in childhood.