In these cases, the mediastinal germ cell tumor develops before or concomitantly with but not after acute megakaryoblastic leukemia. The three most common genetic aberrations in the bone marrow cells of these individuals (representing ~65% of all cases) are inversions in the long arm of chromosome 12, trisomy 8, and an extra X chromosome.
In these instances, mediastinal germ cell tumors arise before or at the same time as acute megakaryoblastic leukemia but not after it. The most frequent genetic abnormalities in the bone marrow cells of these individuals (representing ~65% of all cases) are chromosome 12 inversions, trisomy 8, and an extra X chromosome.