الفهرس 
Acute Lymphoblastic leukemia.
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Abstract
Acute lymphoblastic leukemia (ALL) is a malignant clonal disease of the bone marrow in which early lymphoid precursors proliferate and replace the normal hematopoietic cells of the marrow.
In Egypt, ALL is the most common malignancy of childhood; it represents 23.3% of all pediatric malignancies and 75% of pediatric leukemias as reported by the National Cancer Institute, Cairo University.
The TCR genes are located on chromosomes 7 and 14. The genes encoding the T-cell receptor alpha (TCRA /TCRα), T- cell receptor delta (TCRD/ TCRδ) chain are located on chromosome 14q11–12, whereas the T-cell receptor beta (TCRß / TCRB) and T-cell receptor gamma (TCRγ / TCRG) genes are located at chromosomal positions 7q32–35 and 7p15, respectively.
Translocations involving the TCR genes are among the most common abnormalities in T-cell ALL, whereas TCR gene rearrangements are found at a lower frequency in patients with B-lymphoid markers. T-cell ALL is somewhat peculiar in that the majority of patients do not have a cytogenetically detectable chromosomal abnormality.
Methods of detection of TCR gene rearrangement in ALL includes: PCR, FISH by Break-apart FISH, Flow cytometry, Southern Blot Analysis, Karyotypic analysis, DNA microarray platforms, and Single-Strand Conformational Polymorphism (SSCP).
The present study was done on 40 patients and aimed to detect the alpha/delta receptor (14q11) gene rearrangement by dual color break-apart FISH assay in ALL and its relation to patient outcome and prognosis
All the patients were subjected to complete history, clinical examination and laboratory. Moreover, we have tested the expression of TCRαδ (14q11) gene rearrangements by FISH break apart assay on Peripheral blood or Bone marrow samples at diagnosis of the disease (before starting therapy). Risk assessment and follow up of patients was carried out to detect the outcome of the disease.