Which information about the Philadelphia chromosome in leukemia is accurate
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More than 95% of people with CML have what is called the “Philadelphia chromosome.” These patients have Ph+ CML, which stands for Philadelphia chromosome–positive chronic myeloid leukemia. The name of the chromosome comes from where it was first discovered by researchers at the Fox Chase Cancer Center and the University of Pennsylvania, both in Philadelphia. Show
What are the symptoms of Ph+ CML?Many people with Ph+ CML do not have any symptoms of the disease. Indeed, one of the most common signs of the disease is a high white blood cell count—which may be found during a routine blood test. What causes Ph+ CML?You’re not born with Ph+ CML. It’s also not handed down from one generation to the next. So what causes the disease? Ph+ CML has to do with a change in chromosomes in your body. As your cells wear out, they make copies of themselves. Each cell copies everything inside it, including its chromosomes. The cell then splits in 2—creating 2 identical cells. Although it’s not known why, sometimes a mistake happens when the cell is copying itself. For example: ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Chronic Myeloid Leukemia. Use the menu to see other pages. Think of that menu as a roadmap for this complete guide. About leukemiaLeukemia is a cancer of the blood. Leukemia begins when healthy blood cells change and grow out of control. Chronic myeloid leukemia (CML) is a cancer of the blood-forming cells, called myeloid cells, found in the bone marrow. Bone marrow is the spongy, red tissue in the inner part of large bones. CML most often causes an increase in the number of white blood cells, such as neutrophils or granulocytes, that normally fight infection. It is also sometimes called chronic granulocytic, chronic myelocytic, or chronic myelogenous leukemia. About the Philadelphia chromosomePeople with CML have a genetic mutation or change in their bone marrow cells. It is called a translocation. A translocation is when part of a long strand of genes called a chromosome breaks off and reattaches to another chromosome. In CML, part of chromosome 9 breaks off and bonds to a section of chromosome 22, forming the Philadelphia chromosome or Ph chromosome. The Ph chromosome is made up of 2 genes called BCR and ABL that join together into a single fusion gene called BCR-ABL. It is found only in the blood-forming cells, not in other organs of the body. The BCR-ABL gene causes myeloid cells to make an abnormally activated enzyme. Specifically, it is a tyrosine kinase enzyme. This abnormally activated enzyme is called a fusion protein and allows white blood cells to grow out of control. This genetic change develops from damage that occurs by chance after a person is born. There is no risk that a person will pass on this gene to their children. About CMLOrdinarily, the number of white blood cells is tightly controlled by the body—more white blood cells are produced during infections or times of stress, but then the numbers return to normal when the infection is cured. In CML, the abnormal BCR-ABL enzyme is like a switch that is stuck in the “on” position—it keeps stimulating the white blood cells to grow and multiply. In addition to increased white blood cells, the number of blood platelets that help the blood to clot often increase. And, the number of red blood cells, which carry oxygen, may decrease. Looking for More of an Introduction?If you would like more of an introduction, explore these related items. Please note that these links will take you to other sections on Cancer.Net:
The next section in this guide is Statistics. It helps explain the number of people who are diagnosed with CML and general survival rates. Use the menu to choose a different section to read in this guide. Chronic myelogenous leukemia (CML) is an uncommon type of cancer of the bone marrow — the spongy tissue inside bones where blood cells are made. CML causes an increased number of white blood cells in the blood. The term "chronic" in chronic myelogenous leukemia indicates that this cancer tends to progress more slowly than acute forms of leukemia. The term "myelogenous" (my-uh-LOHJ-uh-nus) in chronic myelogenous leukemia refers to the type of cells affected by this cancer. Chronic myelogenous leukemia can also be called chronic myeloid leukemia and chronic granulocytic leukemia. It typically affects older adults and rarely occurs in children, though it can occur at any age. Advances in treatment have contributed to a greatly improved prognosis for people with chronic myelogenous leukemia. Most people will achieve remission and live for many years after diagnosis. Products & Services
SymptomsChronic myelogenous leukemia often doesn't cause signs and symptoms. It might be detected during a blood test. When they occur, signs and symptoms may include:
When to see a doctorMake an appointment with your doctor if you have any persistent signs or symptoms that worry you. Request an Appointment at Mayo Clinic Causes Close How the Philadelphia chromosome formsHow the Philadelphia chromosome formsAn abnormal chromosome called the Philadelphia chromosome is associated with chronic myelogenous leukemia. Your cells each contain 23 pairs of chromosomes that are made of DNA and hold the instructions for every cell in your body. The Philadelphia chromosome forms when chromosome 9 and chromosome 22 break and exchange portions. This creates an abnormally small chromosome 22 and a new combination of instructions for your cells that can lead to the development of chronic myelogenous leukemia. Chronic myelogenous leukemia occurs when something goes awry in the genes of your bone marrow cells. It's not clear what initially sets off this process, but doctors have discovered how it progresses into chronic myelogenous leukemia. An abnormal chromosome developsHuman cells normally contain 23 pairs of chromosomes. These chromosomes hold the DNA that contains the instructions (genes) that control the cells in your body. In people with chronic myelogenous leukemia, the chromosomes in the blood cells swap sections with each other. A section of chromosome 9 switches places with a section of chromosome 22, creating an extra-short chromosome 22 and an extra-long chromosome 9. The extra-short chromosome 22 is called the Philadelphia chromosome, named for the city where it was discovered. The Philadelphia chromosome is present in the blood cells of 90 percent of people with chronic myelogenous leukemia. The abnormal chromosome creates a new geneThe Philadelphia chromosome creates a new gene. Genes from chromosome 9 combine with genes from chromosome 22 to create a new gene called BCR-ABL. The BCR-ABL gene contains instructions that tell the abnormal blood cell to produce too much of a protein called tyrosine kinase. Tyrosine kinase promotes cancer by allowing certain blood cells to grow out of control. The new gene allows too many diseased blood cellsYour blood cells originate in the bone marrow, a spongy material inside your bones. When your bone marrow functions normally, it produces immature cells (blood stem cells) in a controlled way. These cells then mature and specialize into the various types of blood cells that circulate in your body — red cells, white cells and platelets. In chronic myelogenous leukemia, this process doesn't work properly. The tyrosine kinase caused by the BCR-ABL gene allows too many white blood cells to grow. Most or all of these cells contain the abnormal Philadelphia chromosome. The diseased white blood cells don't grow and die like normal cells. The diseased white blood cells build up in huge numbers, crowding out healthy blood cells and damaging the bone marrow. Risk factorsFactors that increase the risk of chronic myelogenous leukemia:
Family history is not a risk factorThe mutation that leads to chronic myelogenous leukemia isn't passed from parents to children. This mutation is believed to be acquired, meaning it develops after birth. By Mayo Clinic Staff Chronic myelogenous leukemia care at Mayo Clinic Request an Appointment at Mayo Clinic Diagnosis & treatment June 11, 2021 Share on: FacebookTwitter Living with chronic myelogenous leukemia?Connect with others like you for support and answers to your questions in the Blood Cancers & Disorders support group on Mayo Clinic Connect, a patient community. Blood Cancers & Disorders DiscussionsHow did you make the final decision to begin HU protocol for ET? 46 Replies Mon, Nov 28, 2022 chevron-rightHigh Platelets 38 Replies Tue, Nov 15, 2022 chevron-rightMGUS monitoring: What tests do you have done regularly? 31 Replies Mon, Nov 07, 2022 chevron-rightSee more discussionsShow references
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AdvertisementMayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. What is the significance of the Philadelphia chromosome and how is it related to leukemia?The Philadelphia chromosome forms when chromosome 9 and chromosome 22 break and exchange portions. This creates an abnormally small chromosome 22 and a new combination of instructions for your cells that can lead to the development of chronic myelogenous leukemia.
How is Philadelphia chromosome diagnosed?Tests to look for the Philadelphia chromosome.
Specialized tests, such as fluorescence in situ hybridization (FISH) analysis and the polymerase chain reaction (PCR) test, analyze blood or bone marrow samples for the presence of the Philadelphia chromosome or the BCR-ABL gene.
What is leukemia Philadelphia chromosome?(FIH-luh-DEL-fee-uh KROH-muh-some) An abnormality of chromosome 22 in which part of chromosome 9 is transferred to it. Bone marrow cells that contain the Philadelphia chromosome are often found in chronic myelogenous leukemia and sometimes found in acute lymphocytic leukemia.
Which of the following molecular techniques would be best to detect presence of Philadelphia chromosomes in the patient with CML?Polymerase chain reaction (PCR)
It can be done on blood or bone marrow samples and can detect very small amounts of BCR-ABL, even when doctors can't find the Philadelphia chromosome in bone marrow cells with cytogenetic testing. PCR can be used to help diagnose CML.
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