Construction of a NotI linking library and isolation of new markers close to the Huntington's disease gene.

Linking clones contain sequences flanking recognition sites for enzymes cutting rarely in mammalian DNA. They can be used to obtain and correlate both physical and genetic mapping information over subregions of mammalian chromosomes. We have constructed and used a NotI linking clone library representing unmethylated NotI sites from HHW693 DNA, a hamster hybrid cell line containing 4p15-4pter and a fragment of 5p as its only human chromosome contribution. Human clones were identified by hybridisation with a cloned human repeat sequence, and localised further to subregions of human chromosome 4p15-4pter using a panel of additional hybrids. Clones from the region distal to the DNA probes (D4S10, D4S43, D4S95) linked to the Huntington's disease mutation, were further analysed. Four markers close to the HD gene: D4S111, D4S113, D4S114 and clone 417 are described here. In addition to serving as markers in physical and genetic mapping experiments, these linking clones provide probes next to cleavable NotI sites, and can therefore be used to screen NotI based chromosome jumping libraries. They also provide indications for potential gene sequences, identifiable as evolutionarily conserved sequences.