Autosomal dominant Stargardt-like macular dystrophy segregating in a largeCanadian family

Background: Inherited macular dystrophies account for a major fraction of t he cases of retinal degenerative disease that lead to permanent blindness. We describe the clinical and genetic findings in a Canadian family with a f orm of macular dystrophy resembling autosomal dominant Stargardt-like macul ar dystrophy. Methods: Standard ophthalmologic examinations were performed in members of a single five-generation Alberta family. Tests of visual acuity and colour vision, fundus photography, fluorescein angiography and electroretinography were performed in 15 affected people. Blood was collected from 24 family m embers, and DNA was extracted for genotyping. Genetic linkage analysis was performed using polymorphic short tandem repeat microsatellite markers loca ted on chromosome 6q, a region containing loci for several macular disorder s. Results: Affected family members display clinical characteristics resemblin g autosomal dominant Stargardt-like macular dystrophy, previously assigned to chromosome 6q (STGD3). Linkage analysis generated a peak lod score of 5. 50 at an estimated recombination fraction of 0.00 for marker locus D6S300. Interpretation: The family described has an autosomal dominant macular dyst rophy that resembles Stargardt-like macular dystrophy, The disease locus fo r this family maps to an interval on chromosome 6q that overlaps that for S TGD3 and other retinal dystrophy loci. These findings provide further evide nce that human chromosome 6q represents a "hot spot" for retinal disorders.