[1] Saarland Univ, Ctr Bioinformat, Saarland Informat Campus E2-1, D-66123 Saarbrucken, Germany
[2] Max Planck Inst Informat, Saarland Informat Campus E1-4, Saarbrucken, Germany
[3] Saarland Univ, Grad Sch Comp Sci, Saarland Informat Campus E1-3, Saarbrucken, Germany
[4] Univ Calif Santa Cruz, UC Santa Cruz Genom Inst, Santa Cruz, CA 95064 USA