PBX1 and Down syndrome: In the primary cohort, we performed a univariate Cox regression analysis for each clinical factor (Table 2) and screened factors with P < 0.1, which included age, WBC count at diagnosis, CNS status at diagnosis, ETV6 RUNX1 fusion status, TRISOMY 4 10 status, karyotype, TCF3 PBX1 fusion status, BCR-ABL1 fusion status, MRD day 29, BMA blasts day 8, Down syndrome, and DNA index.