 The three most common genetic aberrations in the bone marrow cells of these individuals (representing ~65% of all cases) were inversions in the p arm of chromosome 12, trisomy 8, and an extra X chromosome.In several of these cases, the genetic aberrations in the malignant platelet precursor cells were similar to those in the malignant mediastianal germ cells.These results and those of other analyses suggest that the two malignancies derive from a common founding clone of cells (i.e.