**Abstract**

Myeloproliferative syndromes are cell proliferation involving one or more medullary lines without blocking maturation. Chronic myeloid leukemia (CML) is the most common of these syndromes, it corresponds to the monoclonal proliferation of a multipotent stem cell; the myeloblastic or lymphoblastic transformation of CM. has a poor prognosis. The Philadelphia chromosome t(9;22)(q34;q11) is the first cytogenetic abnormality that has been associated with a malignant process. It is found in 89 to 95% of CML. The search for the Philadelphia chromosome (Ph1) has multiple interests: Diagnostic, prognostic and in therapeutic monitoring. The search for the Philadelphia chromosome by molecular cytogenetics makes it possible to remedy the poverty of cell suspensions in metaphase to take up the inconclusive results of classic cytogenetics on nuclei in interphase and to detect residual disease during therapeutic monitoring. Through the literature review, we highlight the importance of the identification of the Philadelphia chromosome in Myeloproliferative Syndromes for the improvement of the quality healthcare of the affected patients.

**Keywords:** Philadelphia chromosome, myeloproliferative syndromes, karyotype, diagnostic and prognostic interest
