Story highlights The therapy would be the first approved treatment in the US to correct an inherited genetic trait

In clinical trials, 27 of 29 participants maintained improved vision for at least three years

(CNN) A US Food and Drug Administration advisory committee unanimously voted Thursday to approve an experimental genetic therapy for patients with a rare inherited eye disease.

Retinal dystrophy due to mutation of the RPE65 gene causes severe visual impairment beginning in infancy. As it progresses, patients experience gradual loss of peripheral vision and central vision. Eventually, the disease leads to blindness.

Voretigene neparvovec, made by Philadelphia-based Spark Therapeutics Inc. and given the brand name Luxturna, is now one step closer to full FDA approval. The agency will make its final decision by January 12. If the verdict is positive, the gene therapy will be the first approved treatment in the US to correct an inherited genetic trait. Some scientists believe an approval could open the door to other treatments that correct flaws in the inherited genome.

Spark believes that 1,000 to 2,000 people in the United States -- 6,000 worldwide -- would be eligible for its gene therapy. Currently, there are no approved treatments for this disease.

In clinical trials, 27 out of 29 participants (93%) demonstrated a gain in functional vision and maintained improved vision for at least three years. No serious adverse events or harmful immune responses have been associated with the gene therapy.

Read More