Survival curves for ADA-SCID in a contemporary cohort receiving FDCT after the year 2000 and without active infection at the time of definitive cellular therapy. The HCT group (n = 33) comprised a wide variety of transplant approaches (Table 4), including patients who did (n = 15) and did not (n = 18) receive ERT before HCT; and a wide variety of donor types (MSD [n = 9], MFD [n = 3], unrelated donors [n = 13], and MMRD [n = 8]), graft sources (bone marrow [n = 21], cord blood [n = 8], and peripheral blood [n = 4)], and conditioning regimens (none [n = 15], RIC [n = 6], and MAC [n = 11]). The contemporary HCT group was compared against patients receiving ERT-GT (n = 33). (A) Five-year EFS for the HCT group was 75.3% (95% CI: 56.5%-86.8%) vs 75.3% (95% CI: 34.3%-92.7%) for the GT group (P = .29, log-rank test). (B) Five-year OS for the HCT group was 90.9% (95% CI: 74.4%-97%) vs 100% (95% CI: 100%-100%) for the GT group (P = .09, log-rank test).