The pathophysiology of MDR3 deficiency is thought to result from (i) a lack of PL protection in the bile against the detergent effect of bile salts, with ensuing damage to hepatocytes and biliary epithelium, bile ductular proliferation, and progressive portal fibrosis; (ii) an increased biliary lithogenicity leading to a cholesterol gallstone disease which may result in bile duct obstruction.3 This evidence concerns the gene ABCB4 and hyperinsulinemic hypoglycemia, familial, 4.