In Central America, nearly 70% of pediatric
cancer is related to hemato-oncologic disorders, especially
acute lymphoblastic leukemia (ALL). Preliminary studies have described a high incidence of childhood
leukemia in these countries; however, no molecular analyses of these
malignancies have yet been carried out. We studied diagnostic samples from 84 patients from the National Children's Hospital in San Jose, Costa Rica (65 precursor B-ALL, 5 T-cell ALL, and 14
acute myeloblastic leukemia). Our methodology included cytogenetic, fluorescent in situ hybridization, and polymerase chain reaction approaches. The observed rate of
leukemia was 52.2 cases per million children per year. Twelve out of 65 (18.4%) precursor B-ALL tested positive for TEL-AML1 and 3 cases for BCR-ABL (4.6%). In addition, we detected 2 patients carrying an E2A-PBX1 transcript (3.1%) and 1 patient with an MLL-AF4 fusion gene (1.5%). None of the T-cell ALL cases were positive for either SIL-TAL1 or HOX11L2. Within 14
acute myeloblastic leukemia patients, we confirmed 2 cases with FLT3-internal tandem duplication+, 1 patient with AML1-ETO, and only 1 case carrying a
PML-RARalpha rearrangement. The present study confirms the relatively high incidence of pediatric
leukemia in Costa Rica and constitutes the first report regarding the incidence of the main molecular alterations of childhood
leukemia in our region.