[Mapping and human genome sequence program].

Until recently, human genome programs focused primarily on establishing maps that would provide signposts to researchers seeking to identify genes responsible for inherited diseases, as well as a basis for genome sequencing studies. Preestablished gene mapping goals have been reached. The over 7,000 microsatellite markers identified to date provide a map of sufficient density to allow localization of the gene of a monogenic disease with a precision of 1 to 2 million base pairs. The physical map, based on systematically arranged overlapping sets of artificial yeast chromosomes (YACs), has also made considerable headway during the last few years. The most recently published map covers more than 90% of the genome. However, currently available physical maps cannot be used for sequencing studies because multiple rearrangements occur in YACs. The recently developed sets of radioinduced hybrids are extremely useful for incorporating genes into existing maps. A network of American and European laboratories has successfully used these radioinduced hybrids to map 15,000 gene tags from large-scale cDNA library sequencing programs. There are increasingly pressing reasons for initiating large scale human genome sequencing studies.