Last year was an important one for Bluebird Bio (NASDAQ: BLUE) as the biotech company earned two key regulatory approvals in the U.S. Despite these wins, the market has hardly rewarded the gene-editing specialist; its shares are down 39% in the past year, and Bluebird's market capitalization is currently just $323 million. The company's newly approved therapies are Zynteglo, which targets transfusion-dependent beta-thalassemia (TDT, a rare blood disorder), and Skysona, a medicine for cerebral adrenoleukodystrophy (CALD, a progressive, pediatric, and fatal neurodegenerative disease). The issue here is whether third-party payers will agree to cover these medicines.