Perfect conserved linkage across the entire mouse chromosome 10 region homologous to human chromosome 21

The distal end of human Chromosome (HSA) 21 from PDXK to the telomere shows perfect conserved linkage with mouse Chromosome (MMU) 10. This region is b ounded on the proximal side by a segment of homology to HSA22q11.2, and on the distal side by a region of homology with HSA19p13.1. A high-resolution PAC-based physical map is described that spans 2.8 Mb, including the entire 2.1 Mb From Pdxk to Prmt2 corresponding to HSA21. Thirty-four expressed se quences are mapped, three of which were not mapped previously in any specie s and nine more that are mapped in mouse For the first time. These genes co nfirm and extend the conserved linkage between MMU10 and HSA21. The ordered PACs and dense STS map provide a clone resource for biological experiments , for rapid and accurate mapping, and for genomic sequencing. The new genes identified here may be involved in Down syndrome (DS) or in several geneti c diseases that map to this conserved region of HSA21.