The MLL leukemia

Acute lymphoblastic leukemia with mixed-lineage leukemia gene (MLL) translocations has a particularly poor prognosis, but it is not clear if host-related factors or tumor-intrinsic biological differences are responsible for these poor survival rates. In December 3 on line Nature Genetics, Scott Armstrong and colleagues from Dana-Farber Cancer Institute, Boston, Massachusetts, show that acute leukemia with MLL translocations has a gene expression profile that identifies them as a unique, new type of leukemia.

Armstrong et al. analyzed RNA on microchips and found that lymphoblastic leukemia with MLL translocations has a gene expression profile consistent with an early hematopoietic progenitor expressing select multilineage markers and individual HOX genes. In addition, clustering algorithms reveal that MLL leukemia can clearly be separated from conventional acute lymphoblastic and acute myelogenous leukemias (Nat Genet 2001, DOI: 10.1038/765).

These results suggest that MLL leukemia is a critical unique entity and "mandates the examination of...