Studying Copy Number Variations in Cell-Free DNA: The Example of AR in Prostate Cancer.

Serum and plasma cell-free DNA (cfDNA) has been shown as an informative noninvasive source of biomarkers for different diseases, including cancer. Starting from the hypothesis that the gain of androgen receptor (AR) gene is a frequent aberration in advanced prostate cancer patients, we analyzed it in cfDNA as a potential predictive biomarker of specific treatments. Here we report a general protocol that may be considered to analyze gene copy number variations in serum or plasma fluids.