1. Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
2. Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030
3. Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas 77030
4. Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
5. Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas 77030
6. Department of Neuroscience, Baylor College of Medicine and Jan and Dan Duncan Neurological Research Institute, Houston, Texas 77030;