Gyrate Atrophy of the Choroid and Retina

Gyrate atrophy is a rare hereditary disease of the eye's retina (the layer of light-sensitive tissue that lines the inside of the eyeball) and choroid (a vascular layer of tissue behind the retina). Degeneration of these structures causes near-sightedness, cataracts and progressive loss of vision. This study will examine eye function and chemical and molecular abnormalities in patients with gyrate atrophy to try to better understand, diagnose, and treat the condition. Patients with other degenerative diseases of the choroid and retina, such as retinitis pigmentosa, choroideremia, and others, will also be studied for comparison. Family members of patients will be studied, when possible, to try to identify the genetic basis of the disease and gain information that will aid in genetic counseling. Study participants will undergo a physical examination and eye examination, including tests of color vision, field of vision, and ability to see in the dark. An electroretinogram and electrooculogram will measure visual cell function. Photographs of the retina will be taken. Blood will be drawn for biochemical study and gene research. Family members who agree to participate in the study will undergo the same eye tests and will also have blood drawn for genetic studies. Patients with gyrate atrophy will also be asked to undergo a small skin biopsy for biochemical and genetic study. They will provide a family history in order to draw a family tree showing how the disease is distributed among family members. Patients with gyrate atrophy may also participate in studies of the effect of vitamin B6 and diet on blood levels of the amino acid ornithine, which is elevated in patients with gyrate atrophy. Participants will take 500 mg of vitamin B6 by mouth every day for 3 to 6 months. If this study confirms a reduction of ornithine levels, then long-term studies of the vitamin as a possible treatment for the disease may be started. After the vitamin B6 study, patients will start a n