An Autosomal Dominant Bull'S-Eye Macular Dystrophy (Mcdr2) That Maps To The Short Arm Of Chromosome 4

PURPOSE. To describe the phenotype of an autosomal dominant macular dystrophy and identify the chromosomal locus.METHODS. Eleven members of a five-generation, nonconsanguineous British family Were examined clinically and also underwent automated perimetry, electrodiagnostic testing, fundus fluorescein angiography, and fundus autofluorescence imaging. Blood samples were taken for DNA extraction and linkage analysis was performed.RESULTS. The phenotype is characterized by bull's-eye macular dystrophy first evident in the first or second decade of life. There is mild visual impairment, central scotomata, and electrophysiological testing indicates that most affected individuals have disease confined to the central retina but older subjects have more widespread rod and cone abnormalities, demonstrated by flash ERG. Genetic linkage analysis established linkage to chromosome 4 at p15.2-16.3 with a maximum lod score of 3.03 at a recombination fraction of 0.00 for marker D4S391. The locus for this autosomal dominant macular dystrophy ties between flanking markers D4S3023 and D4S3022, and overlaps the Stargardt 4 locus.CONCLUSIONS. A new locus was identified for a bull's-eye macular dystrophy on the short arm of chromosome 4.