Table 1. Common recurrent cytogenetic abnormalities in pediatric and adult B-ALL [3, 10, 11].

Risk groups	Cytogenetic abnormalities	Clinical significance	Frequency
Good risk	Hyperdiploidy (>50 chromosomes)	Favorable prognosis	25-30% in children; 7-8% in adults
	t(12;21)/ ETV-RUNX1	Favorable prognosis in children, undetermined in adults	25% in children; 0-4% in adults
Intermediate risk	t(1;19)/E2A-PBX1	Intermediate to favorable prognosis	1-6% in children; 1-3% in adults
	t(5;14)/IL3-IGH	Intermediate	Rare
Poor risk	t (9; 22)/BCR-ABL1	Poor prognosis	1-3% in children; 25-30% in adults
	t(v;11q23)/ KMT2A (MLL) rearrangements	Poor prognosis	2/3 in infants; 1-2% in older children; 4-9% in adults
	Hypodiploidy (<44 chromosomes)	Poor prognosis	6% in children, 7-8% in adults