The first gene therapy to treat genetic disease approved by the U.S. Food & Drug Administration will cost $850,000. Luxturna, from Spark Therapeutics, is designed to partially restore vision in people with a rare form of inherited blindness. The one-time treatment was expected to cost $1 million or more. Spark will offer rebates to insurance companies if patients do not improve in short- or long-term tests of light sensitivity. Spark is also in talks with the Centers for Medicare & Medicaid Services about letting government or commercial drug payers foot the bill in installments.