1. Coriell Institute for Medical Research, Camden, NJ 08103.
2. These authors contributed equally to this work.
3. Divisions of Human Genetics and Orthopaedic Surgery, The Children's Hospital of Philadelphia and Departments of Pediatrics and Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104.
4. School of Life Sciences, Arizona State University, Tempe, AZ 85287 and Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004.
5. Department of Biostatistics & Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104.
6. Department of Medicine UMDNJ-Robert Wood Johnson Medical School, Camden, NJ 08103.