1. ; Laboratory of Molecular Biology; National Institute of Mental Health; Bethesda, Maryland USA
2. Italy
3. ; Division of Medical Genetics, Department of Medicine; McGill University Health Centre; Montreal Canada
4. ; Division of Medical Genetics, Departments of Pediatrics, Human Genetics, Biology and Medicine; McGill University Health Centre, Montreal; Canada
5. ; Division of Medical Genetics, Departments of Pediatrics, Human Genetics and Biology; McGill University Health Centre; Montreal Canada
6. ; Veterans Affairs Medical Center and the Department of Surgery; University of Tennessee; Memphis Tennessee
7. ; Veterans Affairs Medical Center and the Departments of Surgery and Microbiology and Immunology; University of Tennessee; Memphis Tennessee
8. ; Department of Biochemistry and the Clinical Nutrition Research Unit; Vanderbilt University; Nashville Tennessee
9. Veterans Administration Medical Center and George Washington University; USA
10. ; Division of Gastroenterology and Hepatology; University Hospital Nijmegen; Nijmegen The Netherlands
11. ; Department of Medicine; University of Colorado Health Sciences Center; Denver Colorado
12. ; Department of Veterans Affairs Medical Center; Nashville Tennessee USA