The development and progression of acute lymphoblastic leukemia (ALL) is caused by sequential genetic mutations that alter cellular functions. These mutations result in the arrest of lymphoblast development, the precursor cells of lymphocytes, causing them to gain excessive proliferative capacity and inhibiting the production of other blood cells in the bone marrow.

Causes and risk factors for Acute Lymphoblastic Leukemia (ALL) can be generally listed as follows:

While exposure to ionizing radiation, chemical exposure, and viral infections have been implicated in the development of acute lymphoblastic leukemia (ALL), there is no single proven cause.
Familial occurrence of ALL is rarely reported.
Infants with high birth weight have an increased risk of developing ALL within the first five years of life.
Individuals with Down syndrome also have an increased risk of developing ALL.