1. From the Gordon Norrie Centre for Genetic Eye Diseases, National Eye Clinic for the Visually Impaired, Hellerup, Denmark; the
2. Molecular Genetics Laboratory, University Eye Hospital, Tu¨bingen, Germany; the
3. Department of Pathophysiology of Vision and Neuro-Ophthalmology, University Eye Hospital, Tu¨bingen, Germany; and the
4. Institute of Human Genetics, University of Aarhus, Denmark.