Q1: What is chronic granulocytic leukemia a disease? A: Chronic granulocytic leukemia is referred to as slow granulocyte (CML for short). It is a chronic leukemia. It is characterized clinically by a significant increase in granulocytes (both mature and naive), significant enlargement of the spleen, and generally a slow disease course. Weiming Li, Department of Hematology, Wuhan Union Medical College Hospital Most patients present with no obvious symptoms or only non-specific symptoms such as malaise, low fever, night sweats, etc., and are seen because of elevated white blood cells or enlarged spleen found during physical examination. Q2: How is chronic granulocytic leukemia diagnosed? A: Clinically, chronic granulocytosis can be highly suspected in those who are found to have 1) significantly elevated white blood cells while red blood cells and platelets are essentially normal; 2) accompanied by a significantly enlarged spleen; and 3) without obvious symptoms such as hyperthermia or bleeding. Confirmation of the diagnosis requires a bone marrow aspiration to complete bone marrow cytology, chromosome, and BCR/ABL fusion gene testing. It is important to emphasize that chromosomal examination reveals the Ph chromosome (i.e., t(9;22) chromosome translocation) and/or detects the BCR/ABL fusion gene to confirm the final diagnosis of lentile. Typical case 1: Mr. Wang, 43 years old, had a physical examination in his unit. A routine blood test revealed a white blood cell count of 132×109/L (normal value 4-10×109/L), other indicators were basically normal, and ultrasound revealed a significantly enlarged spleen. The physical examination center suggested the patient to come to the hematology department for consultation. After careful history taking, the patient felt a feeling of fullness in the left lower abdomen recently and had night sweats. A bone aspiration was performed, and the cytomorphology was consistent with the chronic phase manifestation of slow-onset granulocytosis, with positive Ph chromosome and positive BCR/ABL fusion gene, which finally confirmed the diagnosis of slow-onset granulocytosis. Q3: What is the Ph chromosome (i.e., t(9;22) chromosome translocation) and BCR/ABL fusion gene? A: Ph chromosome, the Philadelphia chromosome, is the characteristic chromosome of chronic granulocytic leukemia and is essentially formed by translocation of the ends of the long arms of chromosomes 9 and 22 to each other. Because the ABL gene is located on the long arm of chromosome 9 and the BCR gene is located on the long arm of chromosome 22, the aforementioned translocation on the long arms of chromosomes 9 and 22 fuses these two otherwise separate genes together to produce an abnormal BCR/ABL fusion gene, which encodes a protein with enhanced tyrosine kinase activity, ultimately leading to the development of slow granulocytosis. Thus the Ph chromosome and the BCR/ABL fusion gene are indicators of a confirmed diagnosis of slow granulation and the cause of its development. In short, chromosomal translocations are the underlying cause of the development of chronic granulomatous leukemia. Q4: Is chronic granulocytic leukemia hereditary? Is it contagious? A: Chronic granulocytic leukemia is an acquired disease caused by environmental factors and is not inherited from parents or passed on to their children. It is not inherited from parents and will not be passed on to their children. Chronic leukemia is also not an infectious disease and will not be passed on to those around you. This article is authorized by Dr. Weiming Lai.