PRPH2 and severe early-childhood-onset retinal dystrophy: To date, mutations in five genes have been reported to be responsible for classic STGD or “Stargardt-like” disease (S1 Table): fatty acid elongase 4 (ELOVL4, MIM: 605512) [6–8], prominin 1 (PROM1, MIM: 604365) [5,9], peripherin 2 (PRPH2, MIM: 179605) [10,11], Bestrophin 1 (BEST1, MIM: 607854) [12] and ATP-binding cassette, sub-family A, member 4 (ABCA4, MIM: 601691) [13].