Albireo Pharma, Inc. announced the U.S. Food and Drug Administration has granted orphan drug designation to lead product candidate A4250, an ileal bile acid transporter inhibitor, for the treatment of biliary atresia, a rare and life-threatening liver disease with no approved pharmacologic treatment option.A4250 now holds orphan drug designations from both the FDA and EMA for the treatment of progressive familial intrahepatic cholestasis, Alagille syndrome, biliary atresia and primary biliary cholangitis. The U.S. Food and Drug Administration grants orphan drug designation to novel drugs that seek to treat a rare disease or condition, and provides 7 years of market exclusivity for the product upon regulatory approval. Albireo estimates that biliary atresia is one of the most common rare pediatric liver diseases, affecting between 4.5 and 8.5 in every 100,000 children born worldwide. Biliary atresia is a disease of the liver and bile ducts with symptoms developing about 2-8 weeks after birth. Damaged or absent bile ducts result in bile and bile acids being trapped inside the liver, quickly resulting in damage and scarring of the liver cells (cirrhosis), and even liver failure. With about 80 % of biliary atresia patients (with or without Kasai hepatoportoenterostomy) needing a liver transplant within the first two decades after birth, biliary atresia is the most common pediatric liver disease for which transplants are done.