The Food and Drug Administration may soon approve two gene therapies with the potential to cure more than 100,000 Americans with debilitating sickle-cell disease. Now the bad news: The Centers for Medicare and Medicaid Services (CMS) may soon limit access to such breakthrough treatments.

Gene therapies fix missing or defective genes. The one-time treatments have the potential to cure inherited disorders with early death sentences. The FDA has approved nine gene therapies for such diseases as Duchenne muscular dystrophy, spinal muscular atrophy and retinal dystrophy.