Submitted: 10/19/08; Accepted: 5/15/09; Posted: 9/22/09
A 5-year-old Amish boy diagnosed at birth as having a defect in intracellular cobalamin metabolism, cobalamin C disease (cb1C), presented to the pediatric ophthalmology service with severe visual impairment. Ophthalmoscopy showed bilateral bulls eye macular lesions. Visual loss occurs from retinal degeneration in cb1C disease. This report highlights the importance of post-natal metabolic testing and ophthalmic evaluation in cb1C disease, especially in high-risk inbred populations.