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 haemophilia, sickle-cell anaemia, 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.