Tuyen Ong is joining Nightstar as executive vice president and chief development officer. Ong comes to Nightstar from South Plainfield, NJ-based PTC Therapeutics (NASDAQ: [[ticker:PTCT]]), where we was chief medical officer. Ong will be based in Lexington, MA, where London-based Nightstar has its U.S. headquarters. The company, which develops treatments for rare congenital retinal diseases, is preparing for Phase 3 clinical trials testing its drug NSR-REP1 as a treatment for choroideremia, a condition characterized by a progressive loss of vision leading to complete blindness.