The Philadelphia chromosome (universally present in CML) is lacking in patients with leukemoid reactions.

费城染色体（一般出现在CML）在白血病样反应中一般不出现。

Philadelphia chromosome formed may result in the generation of the fusion protein BCR ABL, a constitutively activated tyrosine ki nas e which then causes chronic myeloid leukemia (CML).

慢性粒细胞白血病（CML）患者体内有异常染色体形成并产生BCR ABL融合蛋白，该融合蛋白能激活酪氨酸激酶，刺激细胞过度增生导致慢性粒细胞白血病的发生。