Derivative 6 as an additional chromosomal abnormality along with t(15;17): A case report

Acute promyelocytic leukemia (APL) is a type of acute myeloid leukemia (AML) characterized by the presence of t(15;17)(q22;q21) translocation leading to fusion between PML and RARa gene. Treatment combining all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has dramatically improved the prognosis of APL. We report a rare finding of primary clone of t(15;17) followed by a sequential clonal evolution of additional derivative chromosome 6 formation by a two hit mechanism. Our case showed a good clinical response with a four years and nine months event free survival after ATRA and ATO combination therapy in spite of existence of three chromosomal abnormalities stating that targeted therapy overcomes the adverse effects of additional genetic markers. However, close monitoring with assessment for long term prognostic behavior is required.

Cytogenetic investigation in chronic myeloid leukemia: study from an Indian population.

Chronic myeloid leukemia (CML) is a malignant neoplasm of hematopoietic cells characterized by abnormal proliferation of myeloid precursors, decreased rates of self destruction and an arrest in cellular differentiation. The bone marrow and peripheral blood accumulates all forms of mature and immature granulocytes, primarily blast cells. It is the most common type of leukemia seen in India, accounting for 30% of all leukemias. Cytogenetic analysis plays a vital and important role in the diagnosis of CML patients. The present study consists of cytogenetic evaluation of 175 CML cases from the Indian population with ages ranging from 6-86 years (mean of 42.8). The study population included 115 males (65.72%) and 60 females (34.28%) with a Male: Female ratio 1.9:1. Out of the 175 cases, 164 (93.7%) were successfully karyotyped while culture failure was observed for 11 (6.3%). Among the 164 reported cases, 53 (32.3%) showed a normal karyotype while within the 111 (67.7%) abnormal cases, 96 cases (86.5%) showed the presence of Philadelphia (Ph') chromosome with standard translocation t(9;22); Ph'+ve along with secondary aberrations was detected in 9 (8.1%) cases. Variants of Ph' chromosome were detected in only one case (0.9%). Ph'-ve CML with other chromosomal aberrations were detected in 5 (4.5%) cases, including +8, del 20q, del 11q and marker chromosome. Furthermore, we believe that availability of more advanced molecular techniques can be used as a supportive tool in CML diagnosis even though it cannot fully replace cytogenetics, which remains the backbone for laboratory investigation of the disease.