Ph染色体是慢性粒细胞白血病(CML)特有的细胞遗传学标志。该易位所导致的BCR／ABL 融合基因在CML的发病中起关键作用。然而,近年来应用荧光原位杂交技术发现10％～15％的CML在衍生9号染色体易位断裂点附近有较大的序列缺失。该种缺失和Ph易位同时发生,并且和CML的不良预后密切相关,是一项有价值的预后指标。本文就此作一综述。 The Ph chromosome is a unique cytogenetics marker of chronic myeloid leukemia (CML). The translocation-induced BCR / ABL fusion gene plays a key role in the pathogenesis of CML. However, in recent years, fluorescence in situ hybridization revealed that 10% to 15% of CML had a large deletion in the vicinity of the cleavage site on chromosome 9 translocation. This deletion is associated with Ph translocation and is closely associated with poor prognosis of CML and is a valuable prognostic indicator. This article gives a summary of this.