IKZF1(Ikaros) is a transcriptional regulator of B cell development and is believed to have tumor suppressor-like properties. Deletions (whole gene and/or partial gene deletions) of IKZF1 have been reported in approximately 15-28% of BCR-ABL1-Negative_B-cell ALL, 70-90% of BCR-ABL1-Positive B-cell ALL. IKZF1 mutations are also found in approximately 40% of "Ph-like" ALL. Loss of functions mutations (missense, nonsense, frameshift mutations) have also been reported in IKZF1 in ALL and appear to be much less common (less than 5% of cases) than deletions. Deletions and mutations in IKZF1 have been associated with adverse prognosis and greater risk of relapse.