<prompt> Percentage of CML in which Philadelphia chromosome is positive:30-4050-6070-8090-95  <response>: Ans: d 90-95 Ref: Robins, 7th ed, p. 697; Har, 16th ed, p. 478In more than 90 of CML cases karyotyping reveals the so called Philadelphia chromosome which is created by a reciprocal 9;22 q34:q 11 translocation.Few words about CML:CML is characterized by an abnormality called Philadelphia chromosome.ABL protooncogene from chromosome 9 is translocated to chromosome 22 where BCR is present and result in formation of BCR-ABL fusion chromosome gene.Phases of CML: BCR-ABL Decreased ApoptosisIncreased Tyrosine kinase activity Uncontrolled proliferation CML Chronic phaseIncreased TLC with varying degree of immature granulocytes. Circulating blasts 5. Normocytic normoblastic anaemia.Increased platelet count. Low LAP score.BM: Hypercellular 100 with ME ratio 9:1 to 15:1. Marrow blast percentage normal or slightly increased. Characteristic cell - Seablue histiocyte.Accelerated phaseBlast crisisBlood marrow blast 10-20Blood marrow basophilia 20Platelet count 1 lakhAc leukaemia with blast 20LAP score increasedHypersegmented neutrophil Pelger Huet 