Continuum of overlapping clones spanning the entire human chromosome 21q

A new map shows that human chromosome 21q consists of a continuous assemblage of clones that overlap each other. The map was derived from human yeast artificial chromosomes for which sequence-tagged sites served as landmarks that were located by polymerase chain reaction. The yeast artificial contiguous unit begins with pericentromeric loci and terminates with subtelomeric loci of 21q. The map agrees with other physical and genetic mapping evidence and should lead to further research on the form and purpose of particular chromosomes.