1. Department of Pediatrics, The Harvard Medical School, Children's Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115, LXR Biotechnology, 1401 Marina Way South, Richmond, California 94804, Department of Medicine, The Harvard Medical School, Brigham and Women's Hospital, 75 Francis Street, Boston, Massachusetts 02115, and Department of Human Genetics, Mount Sinai School of Medicine, Fifth Avenue at 100th Street, New York, New York 10029