A detailed physical map of a region within human chromosome 16q22.1

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We have previously described a tight cluster of five apparently unrelated genes on human chromosome 16q22.1. An expanded region surrounding this gene cluster has now been mapped using P1 artificial chromosome clones (PACs). This PAC map is currently used to identify and characterize new genes from the q22.1 region of human chromosome 16. Work is also underway to reveal the functions of selected genes in the contig.

The construction of the contig was performed by using probes derived from the end of the starting PACs in repeated library screening. If the region mapped contains large duplicated sequence elements, this chromosome walking could potentially lead to the extension of the map into unlinked chromosomal regions. Such large duplicated sequences of several tens of kilo base pairs, which are shared by several human chromosomes, have previously been reported. To verify the organization of the PAC map, we have therefore performed long-range mapping experiments. High molecular weight human genomic DNA was digested with a panel of rare-cutting restriction enzymes, separated by PFGE, blotted and hybridised with selected probes from the contig. These results demonstrated that the contig faithfully represents the chromosomal region covered by the PACs. Furthermore, clusters of restriction sites for CpG cutters are strong evidence for the presence of CpG islands, which are landmarks for genes. Therefore, the mapping experiments have also resulted in the identification of several genes within human chromosome 16q22.1.

This work is supported by grants from The Norwegian Research Council and The Norwegian Cancer Society (EF and HP), and The Comité du Lotet-Garonne de la Ligue Nationale Contre le Cancer (ML and FDB). PRS was a recipient of an ARC fellowship.