Autoomal dominant targardt-like macular dytrophy: I. Clinical characterization, longitudinal follow-up, and evidence for a common ancetry in familie linked to chromoome 6q14 Original Reearch Article

Purpoe: Characterize the phenotype of autoomal dominant targardt-like macular dytrophy in two familie linked to chromoome 6q14 and determine whether they hare a common ancetry. Method: Two familie panning 10 generation were identified and tudied independently. Participating member were examined and genetic linkage and genotyping performed. Reult: Preenting ymptom included decreaed viion, hemeralopia, and mild photophobia. The ubjective onet of viual lo ranged from age 3 to 50 with a mean of 14 year. A nellen acuity of 20/200 occurred at a mean age of 22 year. Over decade, the macular leion enlarged and viual acuity decreaed to 20/300 to 20/800. The typical phenotype wa well-circumcribed, homogenou atrophy of the retinal pigment epithelium and choriocapillari in the macula, with urrounding yellow fleck and temporal optic nerve pallor. The phenotypic pectrum included a pattern dytrophy-like appearance, diffue geographic atrophy, and extenive fundu fleck. Genotyping revealed that the two familie were linked to chromoome 6q14 and hared a common haplotype panning 21 cM between D6430 and D6300. The two familie were ubequently hown by genealogic invetigation to repreent different branche of a common kindred. Concluion: Familie with autoomal dominant targardt-like macular dytrophy linked to chromoome 6q14 hare a common phenotype and in ome cae can be ditinguihed from imilar dytrophie by inheritance pattern and clinical feature. The finding that thee two familie hared a common ancetor ugget the exitence of a founder effect. Characterization of the gene for autoomal dominant targardt-like macular dytrophy may enable better undertanding of thi condition and elucidation of it potential role in other form of macular degeneration.