FISH at Diagnosis of Childhood Acute Lymphoblastic Leukemia
Zemanová, Michalová, Březinová, Šindelářová, Kurková, Smíšek, Zuna, Trka, S t a r ý
III. interní klinika 1. LF UK a VFN, Praha Ústav hematologie a krevní transfuze, Praha II. dětská klinika 2. LF UK a FNM, Praha
Classical cytogenetic analysis plays an important role in the diagnosis, classificat ion, therapy monitoring and
prognosis of patients with leukemia. Many recurrent cytogenetic abnormalities with major prognostic values have
been described in childhood ALL. Hyperdiploidy and/or t(12;21) are associated with good prognosis, whereas t(9;22)
and/or rearrangements of MLL gene correlate with poor outcome and therefore early detection of these abnormalities
is very important. FISH can overcome some limitations of conventional cytogenetic and molecular-genetic analyses
and due to high sensitivity specific chromosomal aberrations in mitoses and/or interphase nuclei can be detected. In
the Center of Oncocytogenetics of the 3rd Medical Department for assesment of hyperdiploidy and structural
rearrangements we use double-color FISH with centromeric and/or locus-specific probes and complex aberrations
are ascertained by whole chromosome painting probes and multicolor FISH. Among 275 children with ALL examined
during the last 8 years by different FISH methods we found seven patients with translocation t(9;22) and 14 patients
with MLL rearrangements in bone marrow cells. Since 1988 we focus on detection of hyperdiploidy and/or t(12;21).
High hyperdiploidy was found in 35 children, 10 of them had further complex rearrangements. Translocation t(12;21)
was proved in 37 patients and complex rearrangements were found in 22 of them. FISH, cytogenetic and
molecular-genetic analyses become obligatory for the first diagnostic examination as well as for monitoring of
treatment effect in children with ALL.
childhood ALL, FISH, conventional cytogenetics, molecular-genetic methods, mFISH.