sjTRECs rise in the peripheral blood of TK007 patients after HSCT and suicide gene therapy. Absolute counts of sjTRECs per 100 ng of genomic DNA extracted from PBMCs of TK007 patients at different time points during their follow-up and, as control group, from patients who underwent non–T cell–depleted haploidentical HSCT. Pie charts below the graph represent the percentage of patients in whom circulating sjTREC counts were above (in black) or below (in white) the sensitivity of the detection method (3 TREC copies/100 ng of DNA).