ABSTRACT
A substantial number of neuroblastomas have either extrachromosomal dmins, chromosomally integrated homogeneously staining regions (HSRs), or both in subpopulations of cells. These two abnormalities are cytogenetic manifestations of gene amplification. Dmins are the predominant form of amplified DNA in primary tumors, but dmins and HSRs are found with about equal frequency in neuroblastoma cell lines. Although cytogenetic analysis of human neuroblastomas frequently has revealed dmins or HSRs in primary tumors and cell lines, the nature of the amplified sequences was not known until recently. Flow cytometric analyses of the DNA content of neuroblastomas, as well as cytogenetic studies of modal chromosome number, have associated hyperdiploid and triploid karyotypes with lower stages of disease and favorable outcomes. Patterns are emerging, based on cytogenetic, molecular, and flow cytometric analysis, which suggest that neuroblastomas may be assigned to three genetically distinct groups.
