Unusual cytogenetic findings in two patients with t(4;11) acute leukemia

Twenty-three cases of acute lymphoblastic leukemia with translocation t(4;11)(q21;q23): the implication of additional chromosomal aberrations

The translocation t(4;11)(q21;q23) is one of the most common specific chromosomal aberrations in acute lymphoblastic leukemia (ALL), occurring in 2% of childhood and in 5-6% of adult cases. Especially in adults, the t(4;11) is associated with a poor prognosis. In order to determine the significance of clonal chromosome aberrations that occur in addition to t(4;11), we studied the karyotypes and clinical courses of 23 patients with acute lymphoblastic leukemia and a translocation t(4;11)(q21;q23). Additional clonal chromosome aberrations were found in ten patients. An isochromosome i(7)(q10) and a trisomy 6 were observed most frequently as secondary anomalies. Clonal evolution was detected in four of six patients analyzed at diagnosis as well as at relapse. With treatment carried out according to modern risk-adapted therapy protocols, no difference in outcome was observed between patients with clonal chromosome aberrations in addition to t(4;11) at diagnosis and those without.

The der(11) chromosome contains the critical breakpoint junction in the 4;11, 9;11, and 11;19 translocations in acute leukemia

Translocations involving 11q23 are recurring abnormalities in human acute leukemia cells of either lymphoid or myeloid lineage. Analysis of 13 variant translocations associated with four of these [t(4;11), t(6;11), t(9;11) and t(11;19)] reveals that the der(11) chromosome is conserved in all of them and therefore contains the critical genetic rearrangement. The MLL gene (myeloid/lymphoid leukemia) is involved in each of these translocations. It is transcribed from centromere to telomere. The present analysis indicates that the 5' region of MLL on the der(11) is juxtaposed to the coding sequences of genes on each of the other translocation partners.

Acute leukemias with the t(4;11)(q21;q23)

The t(4;11)(q21;q23) has been associated with marked lineage heterogeneity. Most of the reported cases were classified as acute lymphoblastic leukemia (ALL). The t(4;11) is one of the commonest specific chromosomal translocations in ALL, occurring in 2% of childhood and 5% of adult cases. In childhood ALL, this translocation is associated with female sex, age less than 1 year, hyperleukocytosis, CD10-/CD19+ B-precursor cell immunophenotype, and myeloid-associated antigen (CD15) expression. There also appears to be an age-related difference in treatment outcome. Adults had the worst prognosis, and children aged 1 to 9 years appeared to have a better outcome than infants or adolescents. Reported cases of acute myeloid leukemia (AML) or secondary leukemia with the t(4;11) have not been well characterized. It is intriguing that virtually all of the reported cases with secondary leukemia had received epipodophyllotoxins or doxorubicin, agents that affect topoisomerase II and are associated with secondary AML characterized by 11q23 abnormalities. Identification of the involved gene(s) in the t(4;11) will provide a molecular approach permitting more accurate classification of these cases.

Acute lymphoblastic leukemia with t(4;11) in a patient previously exposed to a carcinogen

A case of early B t(4;11)(q21;q23) acute lymphoblastic leukemia (ALL) with low white blood cell (WBC) count, without splenomegaly, short survival time, in a patient previously exposed to benzol is presented. We discuss the relationship between the t(4;11)(q21;q23) and the exposure to a carcinogen.