Bioinformatics Applications Group, UK MRC Human Genome Mapping Project Resource Centre, Hinxton, Cambridge, UK. jison@hgmp.mrc.ac.uk|Bioinformatics Applications Group, UK MRC Human Genome Mapping Project Resource Centre, Hinxton, Cambridge, UK. jison@hgmp.mrc.ac.uk|Bioinformatics Applications Group, UK MRC Human Genome Mapping Project Resource Centre, Hinxton, Cambridge, UK. jison@hgmp.mrc.ac.uk|Bioinformatics Applications Group, UK MRC Human Genome Mapping Project Resource Centre, Hinxton, Cambridge, UK. jison@hgmp.mrc.ac.uk