Mirum Pharmaceuticals Inc.’s (MIRM) Maralixibat, proposed for cholestatic pruritus in Alagille syndrome, in patients one year of age and older, awaits the FDA decision on September 29.Alagille syndrome, or ALGS, is a rare genetic disorder in which bile ducts are abnormally narrow, malformed and reduced in number, which leads to bile accumulation in the liver and ultimately progressive liver disease.About 2,000 to 2,500 children in the U.S. have ALGS. Unbearable pruritus is a debilitating symptom for patients with Alagille syndrome and is present in most affected children by the third year of life.Currently, there is no approved treatment for Alagille syndrome.Six in 10 children affected by ALGS, are said to require a liver transplant or they progress to death by adulthood.If approved, Maralixibat has a market opportunity of more than $500 million in the U.S., according to the company.MIRM closed Friday’s trading at $16.25, up 4.50%.