In a historic move, the Food and Drug Administration on Tuesday approved a pioneering gene therapy for a rare form of childhood blindness, the first such treatment cleared in the United States for an inherited disease.

The approval signals a new era for gene therapy, a field that struggled for decades to overcome devastating setbacks but now is pushing forward in an effort to develop treatments for hemophilia, sickle-cell anemia and an array of other genetic diseases. Yet the products, should they reach patients, are likely to carry stratospheric prices — a prospect already worrying consumer advocates and economists.

Philadelphia-based Spark Therapeutics, which makes the childhood-blindness treatment, said it will not announce the price until January. Analysts speculate it could be as much as $1 million for both eyes.

Earlier this year, the FDA approved two other treatments it considers gene therapy. Those approaches, which target blood cancers, involve removing immune cells from patients, reprogramming them genetically in the lab to attack cancer and returning them to the patients.

The eye remedy cleared Tuesday represents a classic goal... see more