A population of blast expressing CD 10, moderate CD 9, CD 34, Dim-mod CD 19, Dim CD 25, CD 44, CD 45, Dim-neg CD 33, CD 304, variable CD 20, CD 22, CD 27, CD 73, cCD 79α, MPO neagtive.

GTG

46,XY,t(5;9)(q22;q34.1)[18]/46,XY[2].

Interphase FISH done using commercial LSI ABL1 dual color Break Apart Probe (Zytovision) and LSI IKZF1 dual color Deletion Probe (Surefish)

Interphase FISH for ABL1 showed 1Y1R1G indicative of ABL1 rearrangement along with IKZF1 deletion.

ISCN: nuc ish (ABL1×2)(5’ABL1 sep 3’ABL1×1)[190/200] 

Dasatinib, IT Methotrexate, Vincristine, Daunorubicine,

Apart from BCR, various rare fusion partners for ABL1 gene have been reported. We have identified a B-ALL patient with t(5;9)(q23;q34) gene fusion. This gene fusion was previously reported in an adult and paediatric cases.

ABL1 (v-abl Abelson murine leukemia viral oncogene homolog 1) protein has tyrosine kinase function and also involved in protein protein interaction.

SNX2 (Sorting Nexin 2) is an oligomeric protein containing a variety of domains for protein–protein and protein–lipid interactions, such as coiled-coil domains, and reported to be interact with a number of growth factor receptors including epidermal growth factor receptor and c-Met.

This SNX2-ABL1 fusion falls under ABL1 class fusion. The identification of rare ABL1 fusion partners is important because they may respond to tyrosine kinase inhibitors in the same way as ALL patients with a BCR-ABL1 fusion gene.

The present case was diagnosed as B-ALL. Metaphase Fluorescence In Situ Hybridization (FISH) confirmed t(5;9)(q23;q24) which is suggestive of SNX2::ABL1. Additionally IKZF1 deletion was also detected which is known to have poor outcome in B-ALL. The patient was treated with IT Methotraxate, Daunorubicin and Dasatinib. Patient died within one month of treatment, which shows poor sensitivity toward TKIs compared to that of BCR-ABL1 protein. Treatment with TKIs require further investigation to stratify the patients with SNX2-ABL1.