Detection of IKZF1 Deletion Mutation in Patients With Acute Lymphoblastic Leukemia and Its Impact in Therapy

Detection of IKZF1 Deletion Mutation in Patients With Acute Lymphoblastic Leukemia and Its Impact in Therapy

1. To detect IKZF-1 deletion mutations in patients with ALL.
2. To study the impact of IKZF-1 deletion mutation on therapy of ALL.
3. To study the correlation between IKZF-1 deletion mutations and BCR-ABL.

Acute lymphoblastic leukemia (ALL) a malignant transformation and proliferation of lymphoid progenitor cells in the bone marrow, blood and extramedullary sites. While 80% of ALL occurs in children, it represents a devastating disease when it occurs in adults . predisposing factors include exposure to ionizing radiation, pesticides, certain solvents or viruses such as Epstein-Barr Virus and Human Immunodeficiency Virus. However, in the majority of cases, it appears as a de novo malignancy in previously healthy individuals. Chromosomal aberrations are the hallmark of ALL, but are not sufficient to generate leukemia. Characteristic translocations include t(12;21) [ETV6-RUNX1], t(1;19) [TCF3-PBX1], t(9;22) [BCR-ABL1] . More recently, a variant with a similar gene expression profile to (Philadelphia) Ph-positive ALL but without the BCR-ABL1 rearrangement has been identified. In more than 80% of cases of this so-called Ph-like ALL, the variant possesses deletions in key transcription factors involved in B-cell development including IKAROS family zinc finger 1 (IKZF1) . IKZF1 codes Ikaros, which is a member of a family of zinc- finger nuclear proteins that is required for the earliest stages of lymphoid lineage commitment and acts as tumor suppressor. Most IKZF1 mutations (94%) are deletion mutations, and there are rare point mutations resulting in loss of function of Ikaros .

There are two major deletions occur in the IKZF1 gene:

• The first one was characterized by loss of exons 4 to 7 ( 4-7) with breakpoints occurring in introns 3 and 7 on chromosome 7p12.
• The second deletion involved exons 2 to 7 ( 2-7) with a variable pattern of breakpoints in intron 1 and intron 7 in the same region as those of the 4-7 deletion.

IKZF1 mutations in cases of B-ALL are associated with poor prognosis and high risk of relapse. IKZF1 mutations are found in approximately 15% to 20% of pediatric B-ALL cases and in >75% of pediatric BCR-ABL positive ALL cases. The incidences of IKZF1 mutations in adults are approximately 50% in B-ALL cases and approximately 65% in BCR-ABL positive ALL cases .

The presence of either IKZF1 mutation or BCR- ABL has been reported to be an independent risk factor of poor prognosis for patients with B-ALL .

Inclusion Criteria:

• Patients with acute lymphoblastic leukemia.

Exclusion Criteria:

• patients with any other hematological malignancies.
• patients receiving chemotherapy.