| Popis: |
Chromosome rearrangements of chromosome 11 at band 1 1q23 are detected in a high proportion of infant leukemias (l yr) as well as childhood and adult acute leukemlas of both myelold and lymphold types. Molecular and cytogenetic analysis of these tumors has shown that 7-10% of acute lymphoblastic, and 5-6% of acute nonlymphocytic leukemias are involved in this way (1). Leukemias with rearrangements of band 1lq23 typically are CD l0, exhibit blphenotypic or mixed-lineage phenotype, and have a poor response to chemotherapy (2). The gene on chromosome 11 involved in the 1 lq23 rearrangement has been cloned recently (3, 4) and characterized. It is known as MLL (or ALL-1, HRX, HTRX), the gene encodes a 3969-amino acid polypeptide showing areas of homology to the Drosophila trithorax gene, a putative regulator of homeotic genes in segment determination (5). The MLL gene is large and complex, containing two DNA-binding domains consisting of three AT-hook motifs and two multiple zinc-finger domains, and thus has the characteristics of a transcription factor likely to be involved in the regulation of gene expression. |
