Molecular characterization of acute myeloblastic leukemia according to thenew WHO classification: a different distribution in Central-West Spain

Background and Objectives, Molecular analysis has contributed to the identi fication of several non-random chromosomal translocations, such as t(15;17) , t(8:21); inv(16)/t(16;16) and 11q23 abnormalities, typically associated w ith acute myeloid leukemia (AML), The identification of these chromosomal a bnormalities helps not only to define different AML subtypes with distinct prognoses and treatments but also to monitor the disappearance of malignant cells after treatment, Recent reports suggest that the frequency of these alterations may differ according to geographic distribution, However, most of these reports focus on just one or two genetic alterations, which may le ad to some selection bias, Appropriate epidemiological studies should be ba sed on unselected consecutive series of patients in which all relevant gene s are simultaneously analyzed, The aim of the present study was to explore whether or not the incidence of genetic lesions in Spanish AML patients dif fers from that reported in other countries, Design and Methods. In a series of 145 consecutive unselected adult patient s with AML we simultaneously analyzed the presence of 4 genetic abnormaliti es, PML/RAR alpha for t(15;17), AML1/ETO for t(8;21), CBF beta /MYH11 for i nv(16)/t(16;16) and rearrangements of the MLL gene for 11q23 abnormalities. AML were classified using the new World Health Organization (WHO) classifi cation for hematologic malignancies, The techniques used were standardized according to the recommendations of the European BIOMED-I Concerted Action, Results. The PML/RARa transcript was present in 34 patients (23.4%) (23 wer e bcr1, 2 bcr2 and 9 bcr3), The AML1/ETO fusion transcript was detected in only 2 cases (1.4%) both with M2 morphology, but 29 other cases with M2 mor phology were negative. CBF beta /MYH11 transcript was present in 9 cases (6 .2%) eight of them displaying M4E0 morphology, Finally, 5 cases (3.5%) show ed rearrangements of the MLL gene. Our results differ from those reported f rom the United States and North/Central Europe, particularly regarding the incidence of t(15;17) and t(8;21) translocations. In Spain the frequency of t(15;17) is higher while that of t(8;21) is lower, Interpretation and Conclusions. These data add epidemiological information about geographic heterogeneity of such chromosome aberrations in AML and wo uld contribute to the design of specific screening strategies adapted to th e incidence in each country, (C) 2001, Ferrata Storti Foundation.