t(1;19)(q21 or 23;p13)
The t(1;19) or the der(19) from the t(1;19) rearrangement is almost exclusively observed in pre-B cell acute lymphocytic leukemia (ALL) with FAB-L1 morphology. The t(1;19) ALL does not usually show extreme leukocytosis and suggests a relatively poor patient prognosis.
The t(4;11) is almost exclusively observed in early B-cell acute lymphocytic leukemia (ALL-L2). Most patients with the t(4;11) ALL are less than two years old and present with an extremely elevated white blood cell count along with a high percentage of blasts and hepatospenomegaly. It is not uncommon for the t(4;11) ALL to show a biphenotypic immunologic presentation and to develop additional chromosome abnormalities as the disease progresses or during relapse. The prognosis of t(4;11) ALL patients has been reported to be poor.
del (6q)(multiple breakpoint)
Deletion of the chromosome 6 long arm (6q-) is almost exclusively observed in lymphoid disease, including non-Hodgkin’s lymphoma. The 6q- is rarely observed in Hodgkin’s disease. The 6q- is usually accompanied by other chromosome changes and has been reported to indicate a relatively poor patient prognosis.
del(9)(p21 or 22)
Loss of material from the chromosome short arm (9p-) or rearrangements involving the 9 short arm has been most frequently observed in T-cell “lymphomatous” acute lymphocytic leukemia (ALL). Patients usually present with elevated white blood cell counts and enlargement of lymph nodes and spleen. del(9) patients have also been reported to have a relatively poor patient prognosis and frequently exhibit CNS involvement.
t(9;22)(q34;q11 or 12)
When found in ALL, the t(9;22) indicates an extremely poor patient prognosis, particularly if accompanied by monosomy 7.
Hyperdiploidy with 50+ chromosomes
The presence of 50+ chromosomes without chromosome rearrangements or other clinically significant chromosome changes (e.g. 5q- or -7), is usually observed in acute lymphocytic leukemia (ALL) and frequently present in young patients, ages 3-5 years old. Hyperdiploidy of this type has been reported to suggest a relatively poor patient prognosis. The presence of chromosome rearrangements generally suggests a prognosis relative to the type of rearrangement.
Near-haploidy with 26-29 chromosomes
Near-haploidy is a relatively rare and possibly under-reported finding usually observed in early B-cell acute lymphoblastic leukemia (ALL-L2) in children under the age of 17 years. Near-haploidy is frequently associated with extremely poor prognosis.