<prompt> Philadelphia chromosome isChromosome 9-22 translocationChromosome 5-9 translocationIf absent, indicate prognosis is badIt is prognostic factor in ALL  <response>: Ans. a Chromosome 9 - 22 translocation. Ref. Harrisons Medicine, 18th ch.83, Table 83-2 Specific translocation seen in CML is the Philadelphia chromosome Ph which is derived from a reciprocal translocation between chromosomes 9 and 22 with the breakpoint joining the sequences of the ABL oncogene with the BCR gene. The first reproducible chromosome abnormality detected in human malignancy was Philadelphia chromosome. Seen in CML. This occurs by reciprocal translocation involving ABL oncogene, a tyrosine kinase on chromosome 9 being replaced in proximal to BCR on chromosome 22 t 9, 22. Consequences of expression of BCR ABL gene product is activation of signal transudation pathways, leading to cell growth independent of normal external growth factors. Robertsonian translocation is translocation between two acrocentric chromosomes it most often involves 14 21 Reciprocal transactions involve mutual exchanges between any 2 chromosomes.Also note: Cytogenetic changes have been particularly well studied in 1 leukemias, e.g., Philadelphia chromosome translocation in CML ; and 2 lymphomas, e.g., translocations of MYC in Burkitts .These and other translocations are useful for diagnosis, classification, and prognosis.Representative Oncogenes at Chromosomal TranslocationsGene ChromosomeTranslocationMalignancyABL 9q34.1-BCR 22q119;22q34;q11Chronic myeloid leukemiaATF1 12q13 -EWS 22q1212;22q13;q12Malignant melanoma of soft partsBCL1 11q13.3 -1gH 14q3211;14q13;q32Mantle cell lymphomaBCL2 18q21.3 -1gH 14q3214;18q32;q21Follicular lymphomaFLI1 11q24-EWS 22q1211;22q24;q12Ewings sarcomaLCK 1p34 -TCRB 7q351;7p34;q35T cell acute lymphocytic leukemiaMYC 8q24 -IgH14q328;14q24;q32Burkitts lymphoma, B cell acute lymphocytic leukemiaPAX32q35-FKHRALV 13q142;13q35;q14Alveolar rhabdomyosarcomaPAX7lp36KHRALV13q141;13tp36;q14Alveolar rhabdomyosarcomaREL 2p13-NRG 2p11.2-14Inv2p13;pll.2-14Non-Hodgkins lymphomaRET 10q11.2-PKAR1A17q2310;17q11.2;q23Thyroid carcinomaTAL11p32-TCTA 3p211;3p34;p21Acute T cell leukemiaTRK 1q23-1q24 1q31Inv1q23;q31Colon carcinomaWT1 11p13-EWS 22q 1211;22p13;q12Desmoplastic small round cell tumor 