The first step in the detection of gene doping in athletes is purify cell free DNA from the blood. For the blood bank, Sanquin this purification is almost routine work. To learn how the purification and detection of little amounts of abnormal DNA works, we visited the group of experimental immunohematology. We spoke to different persons. Aïcha showed us how fetal DNA in maternal plasma and serum could be detected. Both fetal DNA and doping DNA are present in little amounts behind a huge background noise from genomic DNA. Onno told us about how to sequence DNA from a blood sample. Finally we had a talk with professor van der Schoot. She made us aware of the big noise from genomic DNA, the importance of amplification from the DNA before useful detection was possible and the time difference between injection of the genes and production of the epo-protein. We also discussed about the circulation of the DNA in the blood and the rate of degradation. This helped us with the development of the model where we aim to model the rate of degradation of the EPO and DNA in the blood.