T-cell lymphoblastic leukemia in early childhood presents NOTCH1 mutations and MLL rearrangements.

T-cell acute lymphoblastic leukemia (T-ALL) may affect children in very early age. However, the critical events leading to this brief latency is still unclear. We used standard methods to explore NOTCH1 mutations and other specific molecular markers in 15 early childhood T-ALL cases. Most of them consisted of immature differentiation subtype. Despite being found in a lower frequency than that described for overall pediatric T-ALL, NOTCH1 alterations were the most frequent ones. Other alterations included MLL(+) (n=4), SIL-TAL1(+) (n=3), FLT3 mutation (n=1) and HOX11L2(+) (n=1). Our results suggest that NOTCH1 and MLL abnormalities are primary leukemogenic hits in early T-ALL.