Acute lymphoblastic leukemia (ALL), is a form of leukemia, or cancer of the white blood cells characterized by excess lymphoblasts.

Malignant, immature white blood cells continuously multiply and are overproduced in the bone marrow. ALL causes damage and death by crowding out normall cells in the bone marrow, and by spreading (infiltrating) to other organs. ALL is most common in childhood with a peak incidence at 2–5 years of age, and another peak in old age.

The overall cure rate in older children is about 80%, and about 45%-60% of adults have long-term disease-free survival. Unfortunately, this is not true for newborns like Molly. Leukemia is an uphill battle with much lower chances of survival. Acute refers to the relatively short time course of the disease (being fatal in as little as a few weeks if left untreated) to differentiate it from the very different disease of Chronic Lymphocytic Leukemia which has a potential time course of many years. It is interchangeably referred to as Lymphocytic or Lymphoblastic. This refers to the cells that are involved, which if they were normal would be referred to as lymphocytes but are seen in this disease in a relatively immature (also termed ‘blast’) state.

A trans-location between chromosomes 4 and 11 occurs in about 4% of cases and is most common in infants under 12 months. This makes cure significantly more difficult and, unfortunately, Molly has this trans-location.