**2.7. Copy number (CN) variation analysis**

Three genomic regions located along each of the clusters were chosen for CN estimations of DLK1-DIO3 and C19MC. Assay qBiomarker Copy Number (Qiagen) was used. Genomic DNA from the stromal cell line HS-5 (CRL-11882) was applied as a calibrator. Analysis was performed with 5 μl of SYBR Green Master Mix, 0.5 μl of respective copy number assay, and 2 ng of genomic DNA in a total volume of 10 μl. Relative quantification was achieved by the ΔΔC<sup>t</sup> method.
