(A). 1-D plot of individual probe binding to the panel of different HLA-DR alleles. The ddPCR reactions were carried out with the individual probe against a panel of highly concentrated genomic DNA containing all eight alleles (HLA-DR 01, 03, 04, 07, 08, 11, 13 and 15). (B). CV (%) of each assay with individual probe. The CV is obtained using 8 repetitions within the same run. (C). The absolute copy number of each allele measured from homozygous (HLA-DR04/04) and heterozygous (HLA-DR04/08) genomic DNA with similar amount (2ng).