Acute Lymphoblastic Leukemia (ALL) accounts for approximately 70% of all childhood leukemia cases (ages 0-19 years), making it the most common type of childhood cancer. It has a peak incidence at 2 to 5 years of age. The incidence decreases with increasing age, before increasing again at around 50 years of age.

Specific genetic abnormalities are identified in the majority of cases of B-ALL, either by karyotyping,  fluorescence in situ hybridization (FISH) studies or PCR. Each of the B-ALL genetic subgroups is important to detect and can be critical prognostic markers. The decision for early transplantation may be made if t(9;22), mlL (KMT2A) translocations (including t(4:11), RUNX1 duplication/amplification (iAMP21) or a hypodiploid clone is identified. In contrast, if the ETV6:RUNX1 fusion (t(12:21) is detected, the patient has a favorable prognosis and transplantation is rarely considered.