Undifferentiated immunophenotypes and not expression of BCR-ABL can be associated in adult Mestizo Mexican patients with ALL.

INTRODUCTION: The BCR-ABL t(9;22)(q34;q11) translocation has been identified as a risk factor in de novo acute lymphoblastic leukemia (ALL), but there are other factors that may influence survival in patients not expressing this translocation. OBJECTIVE: To associate expression and non-expression of BCR-ABL with immunophenotype and other clinical features in adult patients with ALL from a Mexican mestizo population. MATERIAL AND METHODS; Peripheral blood samples from 35 adult patients with de novo ALL were used to detect BCR-ABL by reverse transcriptase polymerase chain reaction (RT-PCR) as well as immunophenotype by flow cytometry. RESULTS: In the group of BCR-ABL negative patients (74.28%) two subgroups were identified with the immature immunophenotypes CD34+/CD33+ and/or CD13+, and CD10-/CD34+. In the group of BCR-ABL positive patients (25.72%) leukemic blast cells with a more differentiated immunophenotype compared to the BCR-ABL negative group were found. As regards clinical and biological characteristics, we found survival in months to be very similar and a tendency to high initial leukocyte counts in both groups. CONCLUSIONS: This is the first study conducted on a Mexican mestizo population to report that BCR-ABL negative patients can present a high frequency of undifferentiated immunophenotypes and must therefore be considered as vulnerable as BCR-ABL positive patients.