CLINICAL-FEATURES OF PROGRESSIVE BIFOCAL CHORIORETINAL ATROPHY - A RETINAL DYSTROPHY LINKED TO CHROMOSOME 6Q

Purpose: The gene for progressive bifocal chorioretinal atrophy (PBCRA ) has been linked to chromosome 6q, near the genomic assignment for No rth Carolina macular dystrophy. A study was undertaken to define the c linical features of a large PBCRA pedigree and to determine whether PB CRA and North Carolina macular dystrophy are phenotypically distinct e ntities. Methods: Fifteen affected individuals from 1 large family wer e examined clinically, which included angiography and electrophysiolog ic studies. Results: The PBCRA is an autosomal dominant chorioretinal dystrophy of early onset characterized by large atrophic macular and n asal retinal lesions, nystagmus, myopia, poor vision, and slow progres sion. A large atrophic macular lesion and nasal subretinal deposits ar e evident soon after birth. An atrophic area nasal to the optic nerve head appears in the second decade, which enlarges progressively. Elect ro-oculographic and electroretinographic studies indicated marked, dif fuse abnormalities of rod and cone function. Fluorescein and indocyani ne green angiography showed a large circumscribed area of macular chor oidal atrophy with staining of deposits in the peripheral retina. In a ddition to previously documented features, nasal retinal abnormalities from a few weeks of age, marked photopsia in a number of patients, an d retinal detachments in three eyes are reported as new features of th e disease. Conclusions: An extended description of PBCRA is presented highlighting that the phenotype is distinct from North Carolina macula r dystrophy, although some phenotypic similarities exist between the t wo conditions. These disorders may be the result of different mutation s on the same gene or nearby genes.