A 60 year old man presented with fatigue, weight loss and heaviness in left hypochondrium for 6 months. The hemogram showed Hb. 10gm/dL, TLC 5 lakhs/mm3, platelet count 4 lakhs/mm3, DLC; neutrophil 55%, lymphocutes 4%, monocytes 2%, basophils 6%, metamyelocytes 10%, myelocytes 18%, promyelocytes 2% and blast 3%. The most likely cytogenetic abnormality in this case is:
Answer is B (t (9; 22) The patient in question is a case of chronic myeloid leukemia (CML) And the characteristic cytogenetic abnormality in CML is the t (9; 22) translocation resulting in the Philadelphia chromosome The diagnosis of CML is suggested by the characteristic laboratory feature (strikingly elevated WBC count with mature forms dominating the picture, associated basophilia and less that 5% blasts and promyelocytes) and suppoed by the clinical features (non specific symptoms of fatigue and weight loss along with heaviness in left hypochondrium suggesting massive splenomegaly which is characteristic of CML) Cytogenetic Abnormality in CML CML is characterized by a reciprocal translocation between chromosome 9 and 22 t (9:22) This translocation results in the fusion of BCR gene on chromosome 22 with AB L gene (protoncogene) located on chromosome 9 forming the BCR-ABL fusion gene The abl gene on chromosome 9 is translocated to bcr site on chromosome 22 The bcr-abl gene is the hallmark of CML and may be detected in peripheral blood Refer previous question for characteristic laboratory findings in CML
t (1; 21)
t (9; 22)
t (15; 17)
Trisomy 21