Center for Genomics and Bioinformatics, Karolinska Institutet, 17177 Stockholm, Sweden. Alistair.Chalk@cgb.ki.se|Center for Genomics and Bioinformatics, Karolinska Institutet, 17177 Stockholm, Sweden. Alistair.Chalk@cgb.ki.se|Center for Genomics and Bioinformatics, Karolinska Institutet, 17177 Stockholm, Sweden. Alistair.Chalk@cgb.ki.se