On the other hand, fluorescence in situ hybridization (FISH) for the RUNX1/RUNX1T1 (formerly AML1/ETO) rearrangement revealed 86% interphase nuclei with one fusion signal, which was found to be on the long arm of chromosome 8 on metaphase FISH, indicating the RUNX1/RUNX1T1 rearrangement by cryptic insertion of the RUNX1 gene.     ///    Acute myeloid leukemia with del(X)(p21) and cryptic RUNX1/RUNX1T1 from ins(8;21)(q22;q22q22) revealed by atypical FISH signals..     ///    "In addition to the cryptic RUNX1/RUNX1T1 rearrangement, this is the first report of partial deletion of an X chromosome as an additional cytogenetic aberration in AML with RUNX1/RUNX1T1.. "