Comparative Investigation of Conventional Cytogenetic and Fluorescence in situ Hybridization in Children with Acute Lymphoblastic Leukemia

Abstract

Acute lymphoblastic leukemia (ALL) is the most common malignancy in childhood. Chromosomal aberrations are independent prognostic factors. Conventional cytogenetics is routinely used in the initial assessment. Nevertheless, karyotyping is often hampered by low mitotic index of malignant cells, poor chromosomal morphology and difficulties in interpretation of chromosome rearrangement. Interphase FISH provides an alternative approach to detect abnormalities in nondividing cells and also is essential for the identification of cryptic abnormalities. In the present study we analysed 56 children with ALL using both cytogenetic and FISH techniques to determine diagnostic accuracy of the both methods. FISH probes for AML1-ELN, BCR-ABL,
and MLL rearrangement were used. Karyotyping was successful in 77% of cases. Cytogenetic study discovered abnormalities in 51% from succeeded karyotyping. FISH revealed chromosomal aberration in 62.5%. FISH confirmed all cases with clonal aberrations, observed with conventional cytogenetics. Among patients with normal karyotype, 24% were detected to have clonal aberrations by FISH. Also, FISH analysis was extremely useful to detection of alteration involving of AML1 and TEL genes. We demonstrate that interphase FISH is available to detect more prognostic important genetic abnormalities than conventional cytogenetic. Cytogenetic analysis combined with FISH produced significant improvements in the sensitivity and accuracy in identification of the of risk stratification of patients.