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Definition of Chromosome 11 childhood leukemia

Chromosome 11 childhood leukemia: A new type of childhood leukemia in which a piece of chromosome 11 has been translocated (broken off and attached itself to another chromosome). Children with this type of leukemia have a particularly poor prognosis (outlook). They have very high white blood counts and a high frequency of central nervous system involvement. They do not respond at all well to the standard therapies for ALL (acute lymphoblastic or lymphocytic leukemia) and often suffer from early relapse after chemotherapy. As many as 80% of infants under 6 months of age with acute leukemia have a translocation affecting chromosome 11 at the 11q23 position- the site of the Mixed Lineage Leukemia (MLL) gene. The name is derived from the observation that Children with chromosome 11 translocation leukemia have gene expression profiles that are different from the profiles of other acute leukemias such as ALL and acute myeloid leukemia. The frequency of such translocations decreases in acute leukemia affecting infants 6 months to 1 year of age and lessens further with advancing age. The MLL translocation positive acute leukemia has distinct clinical and laboratory findings. It is not a subset of ALL.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=19700
Last Editorial Review: 9/20/2012

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