Percentage of CML in which Philadelphia chromosome is positive:

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 10-20%Blood/ marrow basophilia >20%Platelet count <1 lakhA/c leukaemia with blast >20%LAP score increasedHypersegmented neutrophil (Pelger Huet)