[1] Univ London Imperial Coll Sci Technol & Med, Sch Med, Div Biomed Sci, Mol Genet Sect, London SW7 2AZ, England
[2] Univ London Imperial Coll Sci Technol & Med, Sch Med, Western Eye Hosp, Acad Unit Ophthalmol, London SW7 2AZ, England
[3] NICHHD, Unit Genet & Endocrinol, NIH, Bethesda, MD 20892 USA
[4] NEI, Immunol Lab, Sect Gene Therapy, NIH, Bethesda, MD 20892 USA