Genomic DNA from single cells are captured in gel beads in a first step by lysis of the cells within a gel bead (cell bead). In a second step, individual barcoded genomic libraries are produced from the cell beads by WG-PCR amplification within an oil droplet. Cell specific barcoded primers are delivered to each cell bead containing droplet by a primer bearing gel bead. The cell specific genomic libraries are then sequenced in bulk. CNV detection is based on variations of sequence depth.