Assessing mapping progress in the Human Genome Project.

An important goal of the Human Genome Project in the United States is to construct a physical map of the human genome, consisting of unique genomic landmarks at an average spacing of 100 kilobases (kb). When completed (which is projected for the year 1998), the map will consist of 30,000 ordered sites, distributed relatively evenly throughout the genome. Such a map should provide the scientific community with an invaluable resource for the localization and isolation of any human DNA sequence of interest. Although the goal is clear, no generally accepted measures have been adopted by either the scientific community or the funding agencies for assessing progress toward the completion of such a map. To some extent, this is because scientists around the world are using a diverse array of mapping methods--including meiotic (1), radiation hybrid (2), in situ hybridization (3), sequence-tagged site (STS)-content (4), and clone-based fingerprint (5) mapping techn iquestha t might not seem amenable to direct comparison. In important ways, however, the lack of universal standards for measuring mapping progress is hindering efficient completion of the map. Without some ongoing global assessment of progress, how can one distinguish those genomic regions requiring additional work and resources from those that are essentially complete? How can anyone determine which projects are proceeding in the most costeffective manner? We believe that universal measures of mapping progress are both desirable and possible. Although each mapping method has its own special characteristics, they share a fundamental similarity: each involves the ordering of unique sites in the genome. This common feature provides a basis for assessing mapping progress. Below, we outline four measures that should be applied to any mapping project to describe its progress.