Short answer · Medically reviewed summary · Last updated: 2026-05-08
Chronic myelogenous leukemia (CML) is a slow-growing type of blood cancer that originates in the bone marrow, causing the body to produce an excessive number of abnormal white blood cells. It is defined by the presence of a specific genetic mutation known as the Philadelphia chromosome, which drives the overproduction of these cells and crowds out healthy blood components. What is the underlying cause of Chronic myelogenous leukemia? Chronic myelogenous leukemia occurs due to a genetic abnormality called the Philadelphia chromosome.
What is Chronic myelogenous leukemia (CML)
What is Chronic myelogenous leukemia (CML)? Plain-language, medically reviewed definition plus the lived reality told by patients.
Chronic myelogenous leukemia (CML) is a slow-growing type of blood cancer that originates in the bone marrow, causing the body to produce an excessive number of abnormal white blood cells. It is defined by the presence of a specific genetic mutation known as the Philadelphia chromosome, which drives the overproduction of these cells and crowds out healthy blood components.
What is the underlying cause of Chronic myelogenous leukemia?
Chronic myelogenous leukemia occurs due to a genetic abnormality called the Philadelphia chromosome. This is a translocation where pieces of chromosomes 9 and 22 break off and switch places, creating a fusion gene known as BCR-ABL1. This gene acts like a "switch" that stays stuck in the "on" position, signaling the bone marrow to produce too many abnormal granulocytes (a type of white blood cell).
Who is typically affected by Chronic myelogenous leukemia?
Chronic myelogenous leukemia is primarily a disease of adulthood, with a median age of diagnosis around 64 years old. It is rare in children, accounting for less than 5% of childhood leukemias. While it affects both genders, there is a slightly higher incidence in males compared to females. It is estimated that there are approximately 1 to 2 cases per 100,000 people annually worldwide.
How does the disease progress?
Clinicians classify Chronic myelogenous leukemia into three distinct clinical phases based on the percentage of immature white blood cells (blasts) found in the blood or bone marrow:
- Chronic Phase: The initial, most stable stage, where patients may have few symptoms and the disease is highly manageable.
- Accelerated Phase: A transitional stage where the number of blast cells increases, and symptoms become more pronounced.
- Blast Crisis: The final, most aggressive phase, which behaves similarly to acute leukemia with a high count of immature cells.
How does Chronic myelogenous leukemia differ from other leukemias?
Unlike acute leukemias, which progress rapidly and require immediate, intensive treatment, Chronic myelogenous leukemia is generally slower-moving. The discovery of targeted therapies known as Tyrosine Kinase Inhibitors (TKIs) has transformed Chronic myelogenous leukemia from a life-threatening condition into a manageable chronic disease for the vast majority of patients.
Next steps
- Consult a hematologist-oncologist to discuss TKI therapy options and regular BCR-ABL monitoring.
- Join the 287 members of our Chronic myelogenous leukemia community on DiseaseMaps.org to share experiences and find peer support.
- Maintain a consistent blood work schedule to monitor your treatment response and blood cell counts.
Medical disclaimer: This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician regarding a medical condition.
References
- National Cancer Institute (NCI) - Chronic Myelogenous Leukemia Treatment
- NIH Genetic and Rare Diseases Information Center (GARD) - CML Overview
- Orphanet - Chronic Myeloid Leukemia
- Leukemia & Lymphoma Society (LLS) - Understanding CML
