1. From the Department of Veterans Affairs Iowa City Health Care System, Iowa City, IA(MSY, RHK, MAY), Department of Internal Medicine, University of Iowa, Iowa City, IA(AO, MAY), Department of Pediatrics and Medicine, Harvard Medical School, Ina Sue Perlmutter Laboratory, Children’s Hospital, Boston, MA(BL), Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA(RHK), Ve