ABCA4 and age-related macular degeneration: Notably, The ABCA4 (ABCR) locus on chromosome 1p21, identified for its involvement in autosomal recessive Stargardt disease retinopathy [23,24,25,26,27], was one of the first loci identified as involved in AMD, though not all reports have been consistent [23,24,25,26,27,28,29,30,31].