Abstract for presentation at 11th International Congress of Human Genetics

t(9;22) causes the activation of oncogenes ABL (cr 9) and the BCR (cr 22). This gives as a result the formation of hybrid fusion gene, BCR\ABL. This hybrid gene encodes a protein that increases the tyrosine kinase activity with neoplasic potential. In Costa Rica, several cytogenetic and cytomorphologic techniques are available to diagnose and classify the t(9;22) in children with acute lymphoblastic leukemia (LLA). Nevertheless it is until now that the molecular diagnosis by RT-PCR is available. In this first report we show how combining existing techniques with DNA technology give rise to a much precise diagnosis of the patient and as a consequence a much precise therapeutic strategy to follow. This is the first report done in Central America using RT-PCR as a powerful tool to determine transcripts in children with LLA.
Materials and Methods: From 2003 to 2004, 31 bone marrow samples of children diagnosed with some type of leukemia were received by the CIHATA from National Children Hospital. Total RNA was extracted from all samples using a commercial kit. And the cDNA synthesis was obtained using a commercial kit. PCR and nested PCR using fluorescent primers was done to samples. Determination of t(9;22) was doing by sequencing with Automatic Sequencer ABI Prism 310 and Gene Scan software analysis.
Results and Discussion: To 31 samples, 8 were positives to t(9;22). This results show the applicability of RT-PCR and sequencing as powerful methods to consolidate diagnosis of t(9;22) in children with LLA. Although it is a new approach it complements conventional techniques that already exist. Combined, these methods also offer the possibility to follow the evolution of the disease in the patient.
Conclusions: Nowdays, new techniques are being established in Costa Rica that allow precise and exact diagnosis of LLA in children. As shown in this first report, the combination of existing techniques with DNA technology (RT-PCR) give rise to a much precise diagnosis of the patient and, as a consequence, leads to a much precise therapeutic strategy to follow. The high sensitivivity and specificity of RT-PCR offers high quality information regarding the nature of the disease at a molecular level.