Characterisation of circulating DNA by parallel tagged sequencing on the 454 platform

Background: Fragments of genomic DNA that can be isolated from the blood and body fluids of vertebrates are also known as circulating DNA. This DNA has widely been investigated as a biomarker for cancer and other diseases but the origin and significance of circulating DNA have not been elucidated to date. Methods: We used a parallel tagged sequencing method to sequence circulating DNA obtained from control individuals as well as cancer patients on the GSFLX sequencer (454 life sciences). Results: Circulating DNA sequenced an one 16th of a picotiter plate produced similar to 3600 unique circulating DNA sequences which were distributed over the human genome and a higher frequency of mutations was observed in cancer patients compared to healthy controls. Conclusion: Circulating DNA represents genomic DNA in the blood of an individual, some sequence related differences might be evident between circulating DNA from cancer individuals and controls but distribution over the genome is similar. (C) 2009 Elsevier B.V. All rights reserved.