JAK2 and Down syndrome: The selected ranges of drug concentrations showing the greatest synergistic effect in BCP-ALL cell lines were used as a reference for treating ex vivo patient blasts with BCP-ALL CRLF2r and positive or not for other characteristics that often co-occur with the rearrangement, such as Down Syndrome, JAK2 mutation and IKZF1 deletion (see Table 1 for clinical and biological data of the patients).