Figure 2.

Complex cytogenetics observed in patient 1. The stem line is shown on the right, which was observed in 11 of 21 cells (see Table 3 for complete nomenclature). Fluorescence in situ hybridization (FISH) studies demonstrate the ring chromosome identified by karyotype originates from Chromosome 3 and contains at least the 3q26 locus (EVI1 gene). The EVI1 probe also localized to a derivative Chromosome 21, which was involved in a three-way translocation with Chromosomes 3 and 19. This was also observed with FISH for RUNX1 (21q22.12), which localized both to the derivative Chromosome 21 and a derivative Chromosome 19. Finally, a terminal deletion of 20q was confirmed in 144/200 interphase cells.