Birdshot retinochoroidopathy in monozygotic twins.

Birdshot retinochoroidopathy is a rare ocular disorder which was named and delineated as a separate clinical entity by Ryan & Maumenee in 1980. We diagnosed birdshot retinochoroidopathy in a monozygotic pair of twins, who were affected with a time interval of 12 years, respectively. These are the first with birdshot retinochoroidopathy to be reported from the Nordic countries and the first report on this disorder in monozygotic twins. Due to night-blindness, visual field defects and a severely affected electroretinogram one of our cases initially was diagnosed as a choroidoretinal dystrophy. Birdshot retinochoroidopathy should be kept in mind as a differential diagnosis in retinitis pigmentosa-like disorders with widespread choroidal involvement. Our cases substantiated the evidence of a strong correlation with the presence of HLA-A29 antigen.