The ddPCR-based assay for CDKN2A copy number analysis was evaluated by mixing DNA from CDKN2A homozygously deleted U87-MG cells with tumor DNA from a glioma that had retained both CDKN2A copies by ddPCR analysis (copy number: 1.85 ± 0.02). This evidence concerns the gene CDKN2A and neoplasm.