We have placed 7,600 cytogenetically defined landmarks on the draft sequence of the human genome to help with the characterization of genes altered by gross chromosomal aberrations that cause human disease. The landmarks are large-insert clones mapped to chromosome bands by fluorescence in situ hybridization. Each clone contains a sequence tag that is positioned on the genomic sequence. This genome-wide set of sequence-anchored clones allows structural and functional analyses of the genome. This resource represents the first comprehensive integration of cytogenetic, radiation hybrid, linkage and sequence maps of the human genome; provides an independent validation of the sequence map^{1, 2} and framework for contig order and orientation; surveys the genome for large-scale duplications, which are likely to require special attention during sequence assembly; and allows a stringent assessment of sequence differences between the dark and light bands of chromosomes. It also provides insight into large-scale chromatin structure and the evolution of chromosomes and gene families and will accelerate our understanding of the molecular bases of human disease and cancer.

1. Department of Pediatrics, University of Pennsylvania, The Children's Hospital of Philadelphia, 3516 Civic Center Boulevard, ARC 516, Philadelphia, Pennsylvania 19104, USA;
2. Roswell Park Cancer Institute, Elm and Carleton Street, Buffalo, New York 14263, USA;
3. National Center for Biotechnology Information, National Library of Medicine, Building 38A/Room 8N805, Bethesda, Maryland 20894, USA;
4. National Cancer Institute, NIH, Building 10/Room 12N214, Bethesda, Maryland 20889-5105, USA;
5. The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, Maryland 20850, USA;
6. Departments of Pediatrics and Human Genetics, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, California 90048, USA;
7. Computer Science Department, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064-1077, USA;
8. Department of Biology, California Institute of Technology, Mail Code 147-75, Pasadena, California 91125, USA;
9. University of California San Francisco Cancer Center, Box 0808, San Francisco, California 94143-0808, USA;
10. Stanford University, Genome Lab, Mail Code 5120, Stanford, California 94305-5120, USA;
11. Sanger Center, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK;
12. Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North C3-168, P.O. Box 19024, Seattle, Washington 98109-1024, USA;
13. Department of Molecular Biotechnology, University of Washington, Box 357730, Seattle, Washington 98195-7730, USA;
14. Departments of Obstetrics and Gynecology and Pathology, Brigham and Women's Hospital, Amory Lab Building 3rd floor, Boston, Massachusetts 02115, USA;
15. Department of Human Genetics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA;
16. Joint Genome Institute-Los Alamos National Laboratory, MS M888 B-N1, P.O. Box 1663, Los Alamos, New Mexico 87545, USA;
17. Joint Genome Institute-Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 84-171, Berkeley, California 94720, USA;
18. Children's Hospital Oakland Research Institute, 747 52nd Street, Oakland, California 94609, USA;
19. Research Genetics, 2130 Memorial Parkway, Huntsville, Alabama 35801, USA;
20. Institute for Systems Biology, 4225 Roosevelt Way NE, Suite 200, Seattle, Washington 98105-6099, USA;
21. Department of Cytogenetics and Molecular Genetics, Women's and Children's Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia;
22. Howard Hughes Medical Institute, Computer Science Department, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064–1077, USA

Correspondence to: B. J. Trask¹² Correspondence should be addressed to B.J.T. (e-mail: Email: btrask@fhcrc.org).