Stargardt disease-1 (STGD1) is an autosomal recessive retinal disease that usually presents as a juvenile-onset macular dystrophy with rapid central visual impairment, progressive bilateral atrophy of the foveal retinal pigment epithelium, and the frequent appearance of yellowish flecks, defined as lipofuscin deposits, around the macula and/or in the central and near-peripheral areas of the retina (summary by Lee et al., 2021). Genetic Heterogeneity of Stargardt Disease Stargardt disease-3 (STGD3; 600110) is caused by mutation in the ELOVL4 gene (605512) on chromosome 6q14, and Stargardt disease-4 (STGD4; 603786) is caused by mutation in the PROM1 gene (604365) on chromosome 4. A locus for Stargardt disease mapped to chromosome 13q34 and designated STGD2 was found to be in error; the disorder in the family in which the linkage was made was correctly mapped to chromosome 6q14 (STGD3). Fundus flavimaculatus (FFM) is an allelic subtype of Stargardt disease that has been associated with mutation in the ABCA4 gene and the PRPH2 gene (179605). FFM has a later age of onset. If loss of visual acuity begins in the first 2 decades, the designation Stargardt disease is preferred; if it begins later in life and has a more progressive course, the term FFM is preferred (Weleber, 1994). An early-onset severe form of retinal dystrophy (CORD3; 604116) is caused by homozygous null mutations in the ABCA4 gene.