In this issue of Cancer Cell, Churchman et al. add to the list of leukemia predisposition genes with the identification and characterization of germline IKZF1 variants in childhood ALL.
In addition, IKZF1 has been implicated in roles involved in some hematologic traits or abnormalities, such as erythrocyte measures, myelofibrosis, and acute lymphoblastic leukemia (ALL), which may be common clinical manifestations or co-occurrence hematological diseases of patients with SLE.
These findings provide a rationale for the surprisingly high frequency of IKAROS deletions in Ph(+) ALL and identify IKAROS-mediated cell cycle exit as the endpoint of an emerging pathway of pre-B cell receptor-mediated tumor suppression.
In contrast, risk of ALL/MLL- was increased in infants homozygous for the IKZF1 variant (OR = 5.1, 95% CI = 1.8-14.5) but the variant did not modify risk of ALL/MLL+.
These SNPs are located at CDKN2A (rs3731217) and IKZF1 (rs4132601), genes frequently lost in ALL, and at CEBPE (rs2239633), ARID5B (rs7089424), PIP4K2A (rs10764338), and GATA3 (rs3824662), genes located on chromosomes gained in high-hyperdiploid ALL.
The multiplex ligation-dependent probe amplification (MLPA) method was used to detect the copy number alterations (CNAs) of IKAROS family zinc finger 1 (<i>IKZF1</i>), paired box 5 (<i>PAX5</i>), ETS variant 6 (<i>ETV6</i>), RB transcriptional corepressor 1 (<i>RB1</i>), BTG anti-proliferation factor 1 (<i>BTG1</i>), early B-cell factor 1 (<i>EBF1</i>), cyclin dependent kinase inhibitor 2A/2B (<i>CDKN2A/2B</i>) and cytokine receptor like factor 2 (<i>CRLF2</i>) genes in 87 adults with acute lymphoblastic leukemia (ALL) in China.
Case-control comparisons revealed dose-dependent associations between ARID5B rs10821936, ARID5B rs10994982, and IKZF1rs11978267 and childhood ALL overall, and B lineage and B lineage hyperdiploid ALL examined separately (all allelic odds ratios ≥1.33, Ptrend≤0.001).
These findings suggest that, in ALL leukemogenesis, loss of CDKN2A and other target genes in the instability region is frequently associated with BCR/ABL1 and IKZF1 dysfunction.
The distribution of genotype rs7073837 in ARID5B significantly differed between ALL and controls (P=0.046), while those of IKZF1 (rs6964823, rs4132601, and rs6944602) and ARID5B (rs10740055 and rs7089424) did not.
Integrated use of minimal residual disease classification and IKZF1 alteration status accurately predicts 79% of relapses in pediatric acute lymphoblastic leukemia.
We identified risk loci for ALL at 7p12.2 (IKZF1, rs4132601, odds ratio (OR) = 1.69, P = 1.20 x 10(-19)), 10q21.2 (ARID5B, rs7089424, OR = 1.65, P = 6.69 x 10(-19)) and 14q11.2 (CEBPE, rs2239633, OR = 1.34, P = 2.88 x 10(-7)).
The present study examines the incidence of IKZF1, CDKN2A/B, PAX5, EBF1, ETV6, BTG1, RB1, JAK2, and Xp22.33 gene deletions/duplications associated with pediatric ALL in Iran and investigates the possible effect of these mutations on drug resistance.
Recent experimental mouse modeling of B-progenitor ALL has shown that IKZF1 alterations have multiple effects, including arresting differentiation, skewing lineage of leukemia from myeloid to lymphoid, and, in Ph+ leukemia, conferring resistance to tyrosine kinase inhibitor (TKI) therapy without abrogating ABL1 inhibition.
Our results demonstrate that the IKAROS promotes PHF2 expression, and suggest that PHF2 <sup>low</sup> expression works with the IKAROS gene deletion to drive oncogenesis of ALL.
We demonstrated the association of IKZF1 polymorphism rs4132601 T/G with increased risk of ALL among Tunisian pediatric cohort, with altered phenotypic changes among ALL patients.
Statistically significant association between genotype at 7p12.2 (IKZF1), 10q21.2 (ARID5B) and the NBS associated locus, 8q21.3 (NBN) and ALL risk was found; odds ratios (ORs), 1.34 (P=0.002), 1.33 (P=0.003), and 1325.21 (P=0.0028), respectively.
Notably, genetic alterations targeting transcriptional regulators of lymphoid development are a hallmark of B-progenitor ALL, and alteration of specific genes in this pathway, such as IKZF1 (encoding IKAROS), are associated with high-risk ALL.
We studied Ikaros gene expression in normal human bone marrow, normal thymocytes, normal fetal liver-derived immature lymphocyte precursor cell lines, eight different ALL cell lines, and leukemic cells from 69 children with ALL (T-lineage ALL, n = 18; B-lineage ALL, n = 51).