الفهرس 
LEUKEMIASOnly 14 pages are availabe for public view
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Abstract
Acute leukemias are a heterogenous group of neoplasms affecting uncommitted or partially committed hematopiotic stem cells.Leukemias are the most common childhood cancers, account for about one third of pediatric malignancies. It may be acute (97%) or chronic (3%). Acute leukemia may be subdivided into ALL, ANLL, AUL and AMLL. Of these subtypes, ALL is considerd the most common form of acute leukemia that constitute about one fourth of all childhood cancers and approximately 75% of all cases of childhood leukemia.The etiology of leukemia remains unknown but many factors are reported to be. associated with occurrence of ALL as genetic factors,environmental factors, chemical carcinogens, viral infection and irnmunodefeciency. Acute leukemia can be classified based on morphologic$ cytochemical, immunologic and cytogenetic characterstics. Cytogenetic analysis plays an important role in the prediction of outcome in childhood ALL, it has diagnostic, prognostic and therapeutic significance. Chromosomal abnormalities in ALL may be numerical or structural.