VCN in granulocytes and PBMCs. Genomic DNA, isolated from (A-B) granulocyte and (C-D) PBMC fractions isolated from peripheral blood samples obtained at serial times after gene therapy as described in “Materials and methods” was analyzed using ddPCR to quantify average VCN. The test results are displayed chronologically (A,C) or grouped by patient for samples 2 years or later after GT (B,D).