1. Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305–5120, USA.
2. Stanford Human Genome Center, Stanford University School of Medicine, Stanford, CA 94305–5120, USA.
3. Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305–5120, USA.
4. Department of Biological Sciences, Stanford University, Stanford, CA 94305–5120, USA.
5. Foundation Jean Dausset-Centre d'Etude du Polymorphisme Humain (CEPH), 75010 Paris, France.