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Abstract

Abstract 

  1. The genes for four different inherited macular dystrophies were recently identified. These include Best vitelliform dystrophy, Doyne honeycomb retinal dystrophy (also known as malattia leventinese), Sorsby macular dystrophy, and Stargardt disease. The first three are autosomal dominant clinical disorders; Stargardt macular dystrophy is an autosomal recessive trait.

  2. The gene for Best disease, VMD2 , encodes bestrophin which is a tetraspan transmembrane protein of unknown function. Both the Doyne ( EGF [epidermal growth factor]-containing fibrillin-like extracellular matrix protein 1 gene and protein (EFEMP1) ) and Sorsby (TIMP-3) genes encode extracellular matrix proteins. The Stargardt macular dystrophy gene, ATP-binding cassette transporter retina-specific gene and protein (ABCR) , encodes an ATP-binding cassette transporter that appears to transport retinaldehyde or a derivative across the rim of the photoreceptor disc membrane, possibly out of the rod outer segment disc to the cytosol of the rod photoreceptor. Each of the four genes is expressed in the retina; VMD2 is expressed specially in retinal pigment epithelium (RPE) and ABCR expressed exclusively in the photoreptor cells.

  3. Mutations of VMD2 , EFEMP1 , and TIMP3 are associated with their respective macular dystrophies. However, homozygous and compound heterozygous mutations of ABCR are associated with a plethora of retinal phenotypes including: Fundus Flavimaculatus, Stargardt disease, combined cone-rod dystrophy, and retinitis pigmentosa (RP19). Some heterozygous ABCR mutations may be associated with a multifactorial disorder, Age-Related Maculopathy.

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