Fundus flavimaculatus and Stargardt disease are thought to represent 2 ends of the spectrum of a disease process characterized by yellowish flecks at the level of the RPE, a generalized vermilion (reddish) color to the fundus on clinical examination, a dark choroid on fluorescein angiography (Fig 11-35A, B; see also Figs 9-7 and 9-8 in BCSC Section 12, Retina and Vitreous), and gradually decreasing visual acuity. The inheritance pattern is generally autosomal recessive, but autosomal dominant forms have been reported as well. Several genetic mutations have been observed in patients with a Stargardt-like phenotype, including the ABCA4, STGD4, ELOV4, and RDS/peripherin genes. Mutations in ABCA4 are responsible for most cases of Stargardt disease. The ABCA4 gene encodes a protein called RIM protein, which is a member of the adenosine triphosphate (ATP)-binding cassette transporter family. It is expressed in the rims of rod and cone photoreceptor disc membranes and is involved in the transport of vitamin A derivatives to the RPE. The most striking feature of Stargardt disease on light and electron microscopy is the marked engorgement of RPE cells (Fig 11-35C, D; see also Fig 9-9 in BCSC Section 12, Retina and Vitreous) with lipofuscin-like, PAS-positive material, with apical displacement of the normal RPE melanin granules.