A variety of loci with interesting patterns of regulation such as imprinted expression, and critical functions such as involvement in tumour necrosis factor pathways, map to a distal portion of mouse chromosome 12. This region also contains disease related loci including the 'Legs at odd angles' mutation (Loa) that we are pursuing in a positional cloning project. To further define the region and prepare for comparative sequencing projects, we have produced genetic, radiation hybrid, physical and transcript maps of the region, with probes providing anchors between the maps. We show a summary of 95 markers and 91 genomic clones that has enabled us to identify 18 transcripts including new genes and candidates for Loa which will help in future studies of gene context and regulation.