Molecular Diagnosis of Chronic Myeloid Leukemia Monitoring Response to Different Types of Treatment

Chronic myeloid leukemia (CML) is one of leukemia types which account for 15 % to 20% of all leukemia cases. Patients are presented with splenomegaly, fever, anemia, fatigue, weight loss, and weakness. It is results from reciprocal translocation (9; 22).This abnormality is called Philadelphia (Ph) chromosome and it is detected in 95% of patients with CML, and in 20% of patients with Acute Lymphocytic Leukemia (ALL). Imatinib mesylate” is the most widely used drug for CML treatment because it targets the abnormal fusion gene. Blood samples were collected from (39) CML patients (19 males and 20 females) from July - November 2009 in The National Center of Hematology/Baghdad. The age range were (8 – 70) years. According to the real time PCR results; the patients were divided into four groups: 1) PCR negative group. 2) PCR positive group on Hydroxyurea treatment 3) PCR positive group on Gleevec® treatment 4) PCR positive group with no treatment (recently diagnosed). Patients were selected randomly. Their RNA was extracted from peripheral blood cells and reverse transcribed into cDNA which was amplified using real time PCR to measure the ratio of BCR-ABL fusion gene in their Philadelphia chromosome. This is to confirm the diagnosis and evaluate the response to the most widely used drugs for CML treatment (Gleevec® 400 mg/d and hydroxyurea 450 mg/d for two months at least). This study excluded CML diagnosis in 10 patients, so other myeloproliferative disorders need to be verified. The group treated with Gleevec® showed a better response than hydroxyurea at the molecular level. Key words: leukemia, chronic myeloid leukemia, polymerase chain reaction, real time PCR, BCR-ABL, quantitative PCR, hydroxyurea, imatinib mesylate, Philadelphia chromosome, tyrosine kinase.