LIG4 and post-transplant lymphoproliferative disease: Of the 8 A-T patients, only 2 survived, both of whom received reduced-intensity conditioning (RIC) with no graft-versus-host disease (GvHD). 6 patients died, primarily from transplant-related complications such as multi-organ failure, viral activation, or PTLD. Survival was markedly higher in patients with other DNA repair disorders like LIG4 and NBS. Across the cohort, RIC had significantly better survival outcomes than myeloablative conditioning (79% vs 41%, p = 0.006).