The Core Hepatic Feature: Bile Duct Paucity
The most famous hallmark of Alagille Syndrome is Bile Duct Paucity. In a healthy liver, a network of ducts carries bile to the gallbladder. In ALGS, these ducts are either too few in number or malformed.
This shortage causes bile to accumulate in the liver cells, leading to:
Cholestasis: A condition where bile flow stops or slows, causing jaundice (yellowing of eyes and skin).
Severe Pruritus: Intense, debilitating itching caused by the buildup of bile salts in the skin.
Xanthomas: Fatty, yellow bumps on the skin (often on joints) due to extremely high cholesterol levels.
Malabsorption: Because bile is needed to digest fats, patients often suffer from deficiencies in fat-soluble vitamins (A, D, E, and K), which can lead to poor growth and weakened bones (rickets).