Stargardt Disease

 The ABCA4 gene (ATP Binding Cassette Subfamily A Member 4) encodes a protein that is essential for the visual cycle, particularly in photoreceptor cells of the retina.

Genetic Details

• Gene Location: Chromosome 1p22.1

• Size: ~150 kb with 50 exons

• Protein Length: ~2,273 amino acids

                                                             

Function

• Protein Product: ABCA4 encodes a transmembrane transporter protein that is part of the ATP-binding cassette (ABC) family.
• Location: Found primarily in retinal photoreceptor outer segment discs (especially in rods and cones).
• Role: Transports retinoid byproducts (like N-retinylidene-phosphatidylethanolamine) from the inner to the outer leaflet of the disc membrane during the visual cycle, preventing accumulation of toxic compounds.

       Mutations in ABCA4 are linked to several autosomal recessive retinal degenerative diseases

                       Stargardt Disease (STGD1) – most common juvenile macular dystrophy

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