This is an open-label, four-cohort, phase 2 study to determine the efficacy of CART19 in pediatric and young adult patients with hypodiploid (Cohort A) or t(17;19) B-ALL (Cohort B), infants with very high risk KMT2A B-ALL (Cohort C), and in patients with central nervous system (CNS) relapse who did not receive cranial radiation (XRT) or bone marrow transplantation (BMT) (Cohort D). Possible procedures include medical record review, apheresis, CART19 infusion, blood draws, physical exams, imaging, and disease assessments through bone marrows and lumbar punctures. If interested in the study or if you have any questions, please contact 267-426-0762.