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Frequent cases of RAS-mutated Down syndrome acute lymphoblastic leukaemia lack JAK2 mutations​

Published on : 08-Aug-2014

ey I Nikolaev, Marco Garieri, Federico Santoni, Emilie Falconnet, Pascale Ribaux, Michel Guipponi, Aoife Murray, Jürgen Groet, Emanuela Giarin, Giuseppe Basso, Dean Nizetic* and Stylianos E Antonarakis* Source: Nature Communication doi:10.1038/ncomms5654 Published online: 2014

Abstract:

Children with Down syndrome (DS) and acute lymphoblastic leukaemia (ALL) have poorer survival and more relapses than non-DS children with ALL, highlighting an urgent need for deeper mechanistic understanding of DS–ALL. Here, using full-exome or cancer genes-targeted sequencing of 42 ALL samples from 39 DS patients, we uncover driver mutations in RAS, (KRAS and NRAS) recurring to a similar extent (15/42) as JAK2 (12/42) mutations or P2RY8-CRLF2 fusions (14/42). RAS mutations are almost completely mutually exclusive with JAK2 mutations (P=0.016), driving a combined total of two-thirds of analysed cases. Clonal architecture analysis reveals that both RAS and JAK2 drove sub-clonal expansions primarily initiated by CRLF2 rearrangements, and/or mutations in chromatin remodellers and lymphocyte differentiation factors. Remarkably, in 2/3 relapsed cases, there is a switch from a primary JAK2- or PTPN11-mutated sub-clone to a RAS-mutated sub-clone in relapse. These results provide important new insights informing the patient stratification strategies for targeted therapeutic approaches for DS–ALL.

NTU Author contact:

Prof Dean Nizetic (d.nizetic@ntu.edu.sg)

Nanyang Technological University, Lee Kong Chian School of Medicine