Cytogenetic analysis of normal and tumour cells of a patient with neuroblastoma

Bone marrow from a one year old child proved to be heavily infiltrated with neuroblastoma cells. Eighteen per cent of metaphases presented abnormal karyotypes, with a chromosome number of 42-48. The typical neuroblastoma karyotypic abnormalities (1p^-, dms, HSR) were not detected, however three major markers were often present: a translocation t(4; 15), a t(14; ?) and also a C-like chromosome. At the same time of the analysis, peripheral blood lymphocytes showed a normal karyotype. We also examined the frequency and induction of fragile sites by 3 different substances, aphidicolin, arabinoside-cytosine and bleomycin, on lymphocytes and bone marrow cells, to verify a possible increased fragility in the bands where the breakpoints are localized on tumour cells. Even though this association was not found, fragile sites on peripheral lymphocytes were highly expressed in 1p36 and 1p32, consistent with our previous reports.