Department of Biomedical Engineering, Department of Ophthalmology and Visual Sciences, Department of Electrical and Computer Engineering, Department of Otolaryngology-Head & Neck Surgery, Carver College of Medicine, Department of Molecular Physiology & Biophysics, Carver College of Medicine, Interdisciplinary Graduate Program in Genetics and Iowa Institute for Human Genetics, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.