Autosomal dominant Stargardt-like macular dystrophy segregating in a large Canadian family

Background: Inherited macular dystrophies account for a major fraction of the cases of retinal degenerative disease that lead to permanent blindness. We describe the clinical and genetic findings in a Canadian family with a form of macular dystrophy resembling autosomal dominant Stargardt-like macular 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 members, and DNA was extracted for genotyping. Genetic linkage analysis was performed using polymorphic short tandem repeat microsatellite markers located on chromosome 6q, a region containing loci for several macular disorders. Results: Affected family members display clinical characteristics resembling 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 dystrophy that resembles Stargardt-like macular dystrophy, The disease locus for this family maps to an interval on chromosome 6q that overlaps that for STGD3 and other retinal dystrophy loci. These findings provide further evidence that human chromosome 6q represents a hot spot for retinal disorders.