Survival after neonatal BMT with or without cytoreduction. Survival was recorded after ADA-deficient mice received neonatal BMT without cytoreduction (n = 14) or with cytoreduction using busulfan given to the pregnant dam (n = 21), or by total body irradiation (TBI) of 100 cGy (n = 25), 200 cGy (n = 22), or 400 cGy (n = 20). Survivorship was subjected to Kaplan-Meier analysis and shows a significant dose-response with increasing doses of TBI (P < .001).