We decided to verify the model of telomere biology in CML proposed by Brümmendorf et al. on the basis of two techniques, TRF method and Q-FISH analysis, and correlation analysis between obtained results and the level of expression of the BCR::ABL1 gene (Brümmendorf et al. 2000). This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.