# What is the Philadelphia chromosome in the context of Chronic Myeloid Leukemia (CML)? Canonical page: https://clinicsjo.com/en/faq/ma-howa-kromosom-filadelfia-fi-syaq-abyidad-dam-naqwi-muzmin-cml Language: en Category: oncology Publisher: ClinicsJo Published: 2026-09-13T08:09:51.199Z Content updated: 2026-09-13T08:09:51.199Z Translation (ar): https://clinicsjo.com/ar/faq/ma-howa-kromosom-filadelfia-fi-syaq-abyidad-dam-naqwi-muzmin-cml The Philadelphia chromosome is a specific genetic change found in the majority of individuals with Chronic Myeloid Leukemia (CML) [\[1\]](). It is not hereditary; rather, it occurs during an individual's lifetime [\[1\]](). To understand this chromosome, it is first necessary to know that every cell in the body contains DNA located within chromosomes, which determine how a cell functions and its appearance [\[2\]](). In the case of Chronic Myeloid Leukemia, an exchange of DNA segments occurs between two different chromosomes: a piece of DNA from chromosome 9 moves to chromosome 22 [\[1\]](). This exchange creates a new gene known as BCR-ABL [\[1\]](). The altered chromosome 22, which carries this fusion gene, is what is called the Philadelphia chromosome [\[2\]](). ## How does the Philadelphia chromosome affect the body? The BCR-ABL gene produces an abnormal protein called tyrosine kinase [\[2\]](). This protein stimulates the bone marrow to produce very large numbers of immature white blood cells, known as blast cells [\[1\]](). These abnormal cells accumulate in the bone marrow and blood, crowding out healthy blood cells and hindering their normal functions [\[1\]](). This can lead to symptoms such as severe fatigue, unexplained weight loss, fever, and drenching night sweats [\[1\]](). ## The importance of the Philadelphia chromosome in diagnosis The detection of the Philadelphia chromosome is crucial in the diagnosis of Chronic Myeloid Leukemia [\[1\]](). This genetic change is identified through special genetic tests performed on blood or bone marrow samples [\[1\]](). These tests include cytogenetic analysis, which examines chromosomes for changes; fluorescence in situ hybridization (FISH); and reverse transcription-polymerase chain reaction (RT-PCR), which measures the amount of genetic material produced by the BCR-ABL gene [\[2\]](). ## Targeted therapies for CML and the role of the Philadelphia chromosome Because of the pivotal role of the abnormal tyrosine kinase protein produced by the BCR-ABL gene, targeted therapies for CML focus on inhibiting this enzyme [\[1\]](). These medications are known as tyrosine kinase inhibitors (TKIs), and they work by blocking the enzyme that causes the bone marrow to produce an excessive number of blast cells [\[1\]](). These inhibitors include drugs such as Imatinib, Dasatinib, and Nilotinib [\[2\]](). These treatments specifically target cancer cells, thereby reducing damage to healthy cells [\[1\]](). ## Treatment monitoring and next steps After starting treatment, periodic monitoring is essential to evaluate the effectiveness of the therapy and track BCR-ABL gene levels. If you are experiencing symptoms such as persistent severe fatigue, unexplained weight loss, fever, drenching night sweats, or pain or a feeling of fullness under the ribs on the left side, it is important to consult your doctor [\[1\]](). These symptoms may be caused by Chronic Myeloid Leukemia or other conditions, and it is important to have them evaluated immediately [\[2\]](). For more information about this disease, you can visit [Chronic Myeloid Leukemia: Understanding the Disease and Modern Treatments (Arabic)](). ## Medical references - [Chronic Myeloid Leukemia]() - [Chronic Myeloid Leukemia Treatment (PDQ®)–Patient Version]() General health education; not a substitute for individualized clinical assessment. Citation URL: https://clinicsjo.com/en/faq/ma-howa-kromosom-filadelfia-fi-syaq-abyidad-dam-naqwi-muzmin-cml#answer