Denaturing- HPLC and HR-1 Melter-Based Detection of ABL Mutations in Patients with Chronic Myelogenous Leukemia (CML).

Imatinib mesylate is the first line of drug for CML since its ability to induce durable remissions in most patients with Philadelphia-positive leukemias and cytogenetic responses in most patients with chronic-phase CML. Although Imatinib mesylate has revolutionized current chronic myeloid leukemia therapy the phenomenon of relapse because of the emergence of resistance were observed. There were well-known mutations in kinase domain that confer resistance despite continued Imatinib mesylate chemotherapy and number of resistance-conferring mutation is increasing. In this study we systematically scanned kinase domain-encoding exon 5, 7, 8, 9, 10 and 11 from genomic DNA of 79 patients with CML to identify novel mutation using denaturing high-performance liquid chromatography (dHPLC) and HR-1 melter (Idaho Technology). In total 15 mutations in the regions were identified and three mutations are found to be novel and two were located in the catalytic domain region (F359I and E374K). Since these two mutations were identified in patients with primary and secondary resistance respectively, it might be classified into resistance-conferring mutation conditional on further functional evaluation. Also we found P499L mutation in the C-terminus and interestingly we detected E478Q in six patients with CML. Analysis with dHPLC and HR-1 screening after PCR amplification proved to be accurate and effective methods to isolate mutation. In addition dHPLC and HR-1 more sensitive compared to PCR direct sequencing methods since two mutations which were not detected by direct sequencing were confirmed only after subcloning of PCR products and sequencing. Taken together, we designed six PCR amplicons encompassing the kinase domain of abl kinase and screened for novel mutations patients with CML. Out of fourteen mutations identified two novel mutations in the catalytic domain need further investigation to understand if they contribute to the acquirance of imatinib mesylate resistance