Hematological Significance of RT-PCR Test for bcr-abl Rearrangement and the Breakpoint Distribution within the Major bcr in Chronic Myelogenous Leukemia Patients / 대한혈액학회지

ABSTRACT

BACKGROUND: Bcr-abl rearrangement is the molecular hallmark of chronic myelogenous leukemia (CML). The test for bcr-abl rearrangement, especially using RT-PCR, is the standard test for the diagnosis of CML. We analyzed hematological significances of bcr-abl rearrangement by RT-PCR and the breakpoint distribution within the major bcr in CML patients. METHODS: From 1994 October to 1997 September, we performed the bcr-abl rearrangement using RT-PCR, in 268 untreated patients with various hematologic diseases, and classified the breakpoints within BCR gene as three types (b2a2, b3a2, e1a2) according to PCR product sizes. We compared hematologic parameters between two groups of b2a2 and b3a2 breakpoints in CML. RESULTS: Among the patients with clinically diagnosed CML, 96.8% (61/63) were bcr-abl positive. In ALL, 52.8% (19/36) were bcr- abl positive. All patients with hematologic diseases other than CML or ALL were bcr- abl negative. Among 61 CML patients with positive bcr-abl rearrangement, 19 patients (31.1%) showed b2a2 type and 42 patients (68.9%) b3a2 type. Patients with b3a2 breakpoints showed more frequent peripheral basophilia (P<0.01) than those with b2a2 type. However, other hematologic parameters were not statistically significant. CONCLUSION: RT-PCR test for bcr-abl rearrangement is a specific and efficient test for the diagnosis of CML. However, the hematological significance of b2a2 and b3a2 types is uncertain in CML.