Bioinformatics Group, MRC Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD, UK. g.gkoutos@har.mrc.ac.uk|Bioinformatics Group, MRC Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD, UK. g.gkoutos@har.mrc.ac.uk|Bioinformatics Group, MRC Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD, UK. g.gkoutos@har.mrc.ac.uk|Bioinformatics Group, MRC Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD, UK. g.gkoutos@har.mrc.ac.uk|Bioinformatics Group, MRC Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD, UK. g.gkoutos@har.mrc.ac.uk|Bioinformatics Group, MRC Mammalian Genetics Unit, Harwell, Oxfordshire OX11 0RD, UK. g.gkoutos@har.mrc.ac.uk