ABCA4 and severe early-childhood-onset retinal dystrophy: Within our patient cohort, the majority of variants were identified in ABCA4, followed by C2orf71 and RP1. Mutations in ABCA4 are predominantly known to cause STGD (currently 610 mutations in ABCA4 have been associated with STGD, source: HGMD), however mutations in ABCA4 are also associated with RP and CORD1, 8, 9.