Intrachromosomal amplification of chromosome 21 (iAMP21) is a rare occurrence in acute myeloid leukemia (AML). We describe here a case of AML with apparent amplification of RUNX1 by cytogenetics and FISH. A 39-year-old female in remission from stage IIIa breast cancer was diagnosed with therapy-related AML (t-AML). The patient's bone marrow was hypocellular for her age (30–40%) with 25% blasts. Cytogenetic analyses revealed a complex karyotype, characterized by rearrangements in chromosomes 1, 5, 17, 20, an additional unidentified marker chromosome, and apparent amplification of chromosome 21. Fluorescence in situ hybridization detected deletions of CKS1B, EGR1, TP53, and apparent amplification of RUNX1 (6–8 signals). Array comparative genomic hybridization (array-CGH) detected amplification of the 5’ non-coding region of RUNX1 and deletion of the 3’ coding region of RUNX1. These results show that this is not a true case of iAMP21 and suggest that RUNX1 is not the primary target of amplification.

染色体21号染色体内扩增（iAMP21）在急性髓细胞性白血病（AML）中很少发生。我们在这里描述了一种通过细胞遗传学和FISH明显扩增RUNX1的AML病例。一名IIIa期乳腺癌缓解期的39岁女性被诊断出患有与治疗相关的AML（t-AML）。患者的骨髓在其年龄（30–40％）中呈低细胞状态，胚泡占25％。细胞遗传学分析揭示了一个复杂的核型，其特征在于染色体1、5、17、20中的重排，另外一个未鉴定的标记染色体以及21号染色体的明显扩增。荧光原位杂交检测到CKS1B，EGR1，TP53的缺失和CKS1B的明显扩增。RUNX1（6-8个信号）。阵列比较基因组杂交（array-CGH）检测到RUNX1的5'非编码区的扩增和RUNX1的3'编码区的缺失。这些结果表明这不是iAMP21的真实情况，并表明RUNX1不是扩增的主要靶标。