Panel a shows the final CD34+ cell products (left-axis) obtained for each patient. Panel b shows the VCN per infused cell post-transduction as determined by quantitative PCR. Transduction was also assessed by analyzing the percentage of vector CFUs PCR-positive for GX1CGD vector detected in the final cell product (Panel c). Vertical bars indicate mean and SD. Panel d displays the total net AUC busulfan exposure obtained by the sum of all pharmacokinetic measurements. Target total exposure of 70,000–75,000 ng ml-1 × h is indicated by the shaded area. AUC, area under the curve; CFU, colony-forming unit; PCR, polymerase chain reaction; SD, standard deviation; VCN, vector copy number.